Episode 7 — DSA with JavaScript / 7.1 — Conditional Statements

7.1.b — Types of Conditional Statements

Overview of conditional types

Conditionals
├── if
├── if-else
├── if — else if — else
├── switch
├── ternary (? :)
└── Logical operators (&&, ||, ??)

This chapter goes deeper into each type with real-world patterns, edge cases, and performance considerations.

1. The `if` statement — deep dive

When to use

You only care about the true path
Guard clauses (early returns)
Feature flags

Block vs expression

// Block form (statement)
if (debug) {
    console.log("Debug mode on");
}

// No block (single statement — avoid in production code)
if (debug) console.log("Debug mode on");

Nested if — and why to avoid it

// BAD: deeply nested
function processOrder(order) {
    if (order) {
        if (order.items.length > 0) {
            if (order.isPaid) {
                if (order.address) {
                    ship(order);
                }
            }
        }
    }
}

// GOOD: guard clauses
function processOrder(order) {
    if (!order) return;
    if (order.items.length === 0) return;
    if (!order.isPaid) return;
    if (!order.address) return;
    ship(order);
}

// C++ equivalent with guard clauses
void processOrder(const Order* order) {
    if (!order) return;
    if (order->items.empty()) return;
    if (!order->isPaid) return;
    if (order->address.empty()) return;
    ship(order);
}

2. The `if-else` statement — deep dive

Pattern: toggle behavior

function toggleTheme(current) {
    if (current === "dark") {
        return "light";
    } else {
        return "dark";
    }
}

Pattern: default value

function getDisplayName(user) {
    if (user.nickname) {
        return user.nickname;
    } else {
        return user.firstName + " " + user.lastName;
    }
}

Pattern: binary search direction

function binarySearchStep(arr, target, lo, hi) {
    const mid = Math.floor((lo + hi) / 2);
    if (arr[mid] === target) {
        return mid;
    } else if (arr[mid] < target) {
        return binarySearchStep(arr, target, mid + 1, hi);
    } else {
        return binarySearchStep(arr, target, lo, mid - 1);
    }
}

int binarySearchStep(vector<int>& arr, int target, int lo, int hi) {
    if (lo > hi) return -1;
    int mid = lo + (hi - lo) / 2;
    if (arr[mid] == target) return mid;
    else if (arr[mid] < target) return binarySearchStep(arr, target, mid + 1, hi);
    else return binarySearchStep(arr, target, lo, mid - 1);
}

3. The `if — else if — else` ladder — deep dive

Pattern: priority-based evaluation

function getShippingMethod(weight, distance, isPremium) {
    if (isPremium) {
        return "express-air";
    } else if (weight > 50) {
        return "freight";
    } else if (distance > 1000) {
        return "standard-air";
    } else if (distance > 100) {
        return "ground";
    } else {
        return "local-delivery";
    }
}

Pattern: input validation chain

function validateAge(input) {
    if (input === null || input === undefined) {
        return "Age is required";
    } else if (typeof input !== "number") {
        return "Age must be a number";
    } else if (!Number.isInteger(input)) {
        return "Age must be a whole number";
    } else if (input < 0) {
        return "Age cannot be negative";
    } else if (input > 150) {
        return "Age seems unrealistic";
    } else {
        return null; // valid
    }
}

#include <string>
#include <optional>
using namespace std;

optional<string> validateAge(int input) {
    if (input < 0) return "Age cannot be negative";
    if (input > 150) return "Age seems unrealistic";
    return nullopt; // valid
}

Performance note

In a long if-else-if chain, put the most likely condition first to minimize the number of comparisons on average.

4. The `switch` statement — deep dive

When switch beats if-else

Scenario	Better choice
Comparing one variable to many constants	`switch`
Range checks	`if-else`
Complex boolean expressions	`if-else`
State machines	`switch`

Pattern: state machine

function nextState(current, event) {
    switch (current) {
        case "idle":
            switch (event) {
                case "START": return "running";
                case "ERROR": return "failed";
                default: return "idle";
            }
        case "running":
            switch (event) {
                case "PAUSE": return "paused";
                case "COMPLETE": return "done";
                case "ERROR": return "failed";
                default: return "running";
            }
        case "paused":
            switch (event) {
                case "RESUME": return "running";
                case "CANCEL": return "idle";
                default: return "paused";
            }
        default:
            return current;
    }
}

State diagram:
  ┌──────┐  START   ┌─────────┐  COMPLETE  ┌──────┐
  │ idle │────────▶│ running │───────────▶│ done │
  └──────┘         └────┬────┘            └──────┘
       ▲    CANCEL      │ PAUSE
       │   ┌────────┐   │
       └───│ paused │◀──┘
           └────────┘ RESUME ──▶ running

Pattern: command dispatcher

#include <iostream>
#include <string>
using namespace std;

void handleCommand(const string& cmd) {
    // C++ doesn't support switch on strings directly.
    // Use if-else or a map. Here's the if-else approach:
    if (cmd == "help")       cout << "Available commands: ..." << endl;
    else if (cmd == "list")  cout << "Listing items..." << endl;
    else if (cmd == "add")   cout << "Adding item..." << endl;
    else if (cmd == "quit")  cout << "Goodbye!" << endl;
    else                     cout << "Unknown command: " << cmd << endl;
}

Grouped cases pattern

function isWeekend(day) {
    switch (day.toLowerCase()) {
        case "saturday":
        case "sunday":
            return true;
        default:
            return false;
    }
}

5. Ternary operator — deep dive

Readability guidelines

// GOOD: simple, readable
const label = count === 1 ? "item" : "items";

// GOOD: assignment with condition
const greeting = isLoggedIn ? `Welcome, ${name}` : "Please log in";

// BAD: complex nested ternary
const result = a > b ? (a > c ? a : c) : (b > c ? b : c);
// Better as:
const result2 = Math.max(a, b, c);

Ternary in template literals

function formatUser(user) {
    return `${user.name} (${user.isAdmin ? "Admin" : "User"})`;
}

Ternary in JSX (React pattern)

function Greeting({ isLoggedIn, name }) {
    return (
        <div>
            {isLoggedIn ? <h1>Welcome, {name}</h1> : <h1>Please sign in</h1>}
        </div>
    );
}

6. Logical operators as conditionals

Short-circuit with &&

// Render only if condition is true
isAdmin && showAdminPanel();

// Guard against null
user && user.profile && user.profile.avatar;
// Modern: user?.profile?.avatar

Default with ||

const port = process.env.PORT || 3000;
const name = userInput || "Guest";

Nullish coalescing ??

// || treats 0, "", false as falsy — sometimes wrong
const count = userCount || 10;        // if userCount is 0, gives 10 (bug!)
const count2 = userCount ?? 10;       // if userCount is 0, gives 0 (correct)

7. Pattern matching (modern approaches)

Object lookup (JS)

Replace long switch/if-else with an object:

const statusMessages = {
    200: "OK",
    201: "Created",
    204: "No Content",
    400: "Bad Request",
    401: "Unauthorized",
    403: "Forbidden",
    404: "Not Found",
    500: "Internal Server Error",
};

function getStatusMessage(code) {
    return statusMessages[code] ?? "Unknown Status";
}

Map lookup (C++)

#include <map>
#include <string>
using namespace std;

string getStatusMessage(int code) {
    static const map<int, string> messages = {
        {200, "OK"}, {201, "Created"}, {204, "No Content"},
        {400, "Bad Request"}, {401, "Unauthorized"},
        {404, "Not Found"}, {500, "Internal Server Error"},
    };
    auto it = messages.find(code);
    return it != messages.end() ? it->second : "Unknown Status";
}

Comparison table: all conditional forms

Form	Use case	Returns value?	Multi-branch?	Fall-through risk?
`if`	Any boolean	No (statement)	No	No
`if-else`	Binary choice	No	No	No
`if-else-if`	Multiple ranges/conditions	No	Yes	No
`switch`	Single value vs constants	No	Yes	Yes
`ternary`	Simple binary expression	Yes	No	No
`&&` / `\|\|`	Short-circuit logic	Yes	No	No
`??`	Null/undefined default	Yes	No	No
Object/Map lookup	Many discrete values	Yes	Yes	No

Scenario bank (types of conditionals)

7.1b-001 — Replace a 3-branch if-else-if with switch (variation 1)

Level: Beginner
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-002 — Replace a switch with object lookup (variation 2)

Level: Beginner
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-003 — Convert nested ternary to if-else (variation 3)

Level: Beginner
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-004 — Use guard clauses to flatten nested ifs (variation 4)

Level: Beginner
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-005 — Replace || default with ?? for numeric values (variation 5)

Level: Beginner
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-006 — Convert if-else to ternary for assignment (variation 6)

Level: Beginner
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-007 — Use && for conditional execution (variation 7)

Level: Beginner
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-008 — Design a state machine with switch (variation 8)

Level: Beginner
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-009 — Validate form inputs with if-else-if chain (variation 9)

Level: Beginner
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-010 — Use fall-through intentionally in switch (variation 10)

Level: Beginner
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-011 — Replace a 3-branch if-else-if with switch (variation 11)

Level: Beginner
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-012 — Replace a switch with object lookup (variation 12)

Level: Beginner
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-013 — Convert nested ternary to if-else (variation 13)

Level: Beginner
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-014 — Use guard clauses to flatten nested ifs (variation 14)

Level: Beginner
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-015 — Replace || default with ?? for numeric values (variation 15)

Level: Beginner
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-016 — Convert if-else to ternary for assignment (variation 16)

Level: Beginner
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-017 — Use && for conditional execution (variation 17)

Level: Beginner
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-018 — Design a state machine with switch (variation 18)

Level: Beginner
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-019 — Validate form inputs with if-else-if chain (variation 19)

Level: Beginner
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-020 — Use fall-through intentionally in switch (variation 20)

Level: Beginner
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-021 — Replace a 3-branch if-else-if with switch (variation 21)

Level: Beginner
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-022 — Replace a switch with object lookup (variation 22)

Level: Beginner
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-023 — Convert nested ternary to if-else (variation 23)

Level: Beginner
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-024 — Use guard clauses to flatten nested ifs (variation 24)

Level: Beginner
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-025 — Replace || default with ?? for numeric values (variation 25)

Level: Beginner
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-026 — Convert if-else to ternary for assignment (variation 26)

Level: Beginner
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-027 — Use && for conditional execution (variation 27)

Level: Beginner
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-028 — Design a state machine with switch (variation 28)

Level: Beginner
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-029 — Validate form inputs with if-else-if chain (variation 29)

Level: Beginner
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-030 — Use fall-through intentionally in switch (variation 30)

Level: Beginner
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-031 — Replace a 3-branch if-else-if with switch (variation 31)

Level: Beginner
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-032 — Replace a switch with object lookup (variation 32)

Level: Beginner
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-033 — Convert nested ternary to if-else (variation 33)

Level: Beginner
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-034 — Use guard clauses to flatten nested ifs (variation 34)

Level: Beginner
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-035 — Replace || default with ?? for numeric values (variation 35)

Level: Beginner
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-036 — Convert if-else to ternary for assignment (variation 36)

Level: Beginner
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-037 — Use && for conditional execution (variation 37)

Level: Beginner
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-038 — Design a state machine with switch (variation 38)

Level: Beginner
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-039 — Validate form inputs with if-else-if chain (variation 39)

Level: Beginner
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-040 — Use fall-through intentionally in switch (variation 40)

Level: Beginner
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-041 — Replace a 3-branch if-else-if with switch (variation 41)

Level: Beginner
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-042 — Replace a switch with object lookup (variation 42)

Level: Beginner
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-043 — Convert nested ternary to if-else (variation 43)

Level: Beginner
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-044 — Use guard clauses to flatten nested ifs (variation 44)

Level: Beginner
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-045 — Replace || default with ?? for numeric values (variation 45)

Level: Beginner
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-046 — Convert if-else to ternary for assignment (variation 46)

Level: Beginner
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-047 — Use && for conditional execution (variation 47)

Level: Beginner
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-048 — Design a state machine with switch (variation 48)

Level: Beginner
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-049 — Validate form inputs with if-else-if chain (variation 49)

Level: Beginner
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-050 — Use fall-through intentionally in switch (variation 50)

Level: Beginner
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-051 — Replace a 3-branch if-else-if with switch (variation 51)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-052 — Replace a switch with object lookup (variation 52)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-053 — Convert nested ternary to if-else (variation 53)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-054 — Use guard clauses to flatten nested ifs (variation 54)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-055 — Replace || default with ?? for numeric values (variation 55)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-056 — Convert if-else to ternary for assignment (variation 56)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-057 — Use && for conditional execution (variation 57)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-058 — Design a state machine with switch (variation 58)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-059 — Validate form inputs with if-else-if chain (variation 59)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-060 — Use fall-through intentionally in switch (variation 60)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-061 — Replace a 3-branch if-else-if with switch (variation 61)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-062 — Replace a switch with object lookup (variation 62)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-063 — Convert nested ternary to if-else (variation 63)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-064 — Use guard clauses to flatten nested ifs (variation 64)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-065 — Replace || default with ?? for numeric values (variation 65)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-066 — Convert if-else to ternary for assignment (variation 66)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-067 — Use && for conditional execution (variation 67)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-068 — Design a state machine with switch (variation 68)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-069 — Validate form inputs with if-else-if chain (variation 69)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-070 — Use fall-through intentionally in switch (variation 70)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-071 — Replace a 3-branch if-else-if with switch (variation 71)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-072 — Replace a switch with object lookup (variation 72)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-073 — Convert nested ternary to if-else (variation 73)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-074 — Use guard clauses to flatten nested ifs (variation 74)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-075 — Replace || default with ?? for numeric values (variation 75)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-076 — Convert if-else to ternary for assignment (variation 76)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-077 — Use && for conditional execution (variation 77)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-078 — Design a state machine with switch (variation 78)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-079 — Validate form inputs with if-else-if chain (variation 79)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-080 — Use fall-through intentionally in switch (variation 80)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-081 — Replace a 3-branch if-else-if with switch (variation 81)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-082 — Replace a switch with object lookup (variation 82)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-083 — Convert nested ternary to if-else (variation 83)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-084 — Use guard clauses to flatten nested ifs (variation 84)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-085 — Replace || default with ?? for numeric values (variation 85)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-086 — Convert if-else to ternary for assignment (variation 86)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-087 — Use && for conditional execution (variation 87)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-088 — Design a state machine with switch (variation 88)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-089 — Validate form inputs with if-else-if chain (variation 89)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-090 — Use fall-through intentionally in switch (variation 90)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-091 — Replace a 3-branch if-else-if with switch (variation 91)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-092 — Replace a switch with object lookup (variation 92)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-093 — Convert nested ternary to if-else (variation 93)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-094 — Use guard clauses to flatten nested ifs (variation 94)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-095 — Replace || default with ?? for numeric values (variation 95)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-096 — Convert if-else to ternary for assignment (variation 96)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-097 — Use && for conditional execution (variation 97)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-098 — Design a state machine with switch (variation 98)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-099 — Validate form inputs with if-else-if chain (variation 99)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-100 — Use fall-through intentionally in switch (variation 100)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-101 — Replace a 3-branch if-else-if with switch (variation 101)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-102 — Replace a switch with object lookup (variation 102)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-103 — Convert nested ternary to if-else (variation 103)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-104 — Use guard clauses to flatten nested ifs (variation 104)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-105 — Replace || default with ?? for numeric values (variation 105)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-106 — Convert if-else to ternary for assignment (variation 106)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-107 — Use && for conditional execution (variation 107)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-108 — Design a state machine with switch (variation 108)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-109 — Validate form inputs with if-else-if chain (variation 109)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-110 — Use fall-through intentionally in switch (variation 110)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-111 — Replace a 3-branch if-else-if with switch (variation 111)

Level: Intermediate
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-112 — Replace a switch with object lookup (variation 112)

Level: Intermediate
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-113 — Convert nested ternary to if-else (variation 113)

Level: Intermediate
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-114 — Use guard clauses to flatten nested ifs (variation 114)

Level: Intermediate
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-115 — Replace || default with ?? for numeric values (variation 115)

Level: Intermediate
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-116 — Convert if-else to ternary for assignment (variation 116)

Level: Intermediate
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-117 — Use && for conditional execution (variation 117)

Level: Intermediate
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-118 — Design a state machine with switch (variation 118)

Level: Intermediate
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-119 — Validate form inputs with if-else-if chain (variation 119)

Level: Intermediate
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-120 — Use fall-through intentionally in switch (variation 120)

Level: Intermediate
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-121 — Replace a 3-branch if-else-if with switch (variation 121)

Level: Advanced
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-122 — Replace a switch with object lookup (variation 122)

Level: Advanced
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-123 — Convert nested ternary to if-else (variation 123)

Level: Advanced
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-124 — Use guard clauses to flatten nested ifs (variation 124)

Level: Advanced
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-125 — Replace || default with ?? for numeric values (variation 125)

Level: Advanced
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-126 — Convert if-else to ternary for assignment (variation 126)

Level: Advanced
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-127 — Use && for conditional execution (variation 127)

Level: Advanced
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-128 — Design a state machine with switch (variation 128)

Level: Advanced
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-129 — Validate form inputs with if-else-if chain (variation 129)

Level: Advanced
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-130 — Use fall-through intentionally in switch (variation 130)

Level: Advanced
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-131 — Replace a 3-branch if-else-if with switch (variation 131)

Level: Advanced
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-132 — Replace a switch with object lookup (variation 132)

Level: Advanced
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-133 — Convert nested ternary to if-else (variation 133)

Level: Advanced
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-134 — Use guard clauses to flatten nested ifs (variation 134)

Level: Advanced
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-135 — Replace || default with ?? for numeric values (variation 135)

Level: Advanced
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-136 — Convert if-else to ternary for assignment (variation 136)

Level: Advanced
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-137 — Use && for conditional execution (variation 137)

Level: Advanced
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-138 — Design a state machine with switch (variation 138)

Level: Advanced
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-139 — Validate form inputs with if-else-if chain (variation 139)

Level: Advanced
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-140 — Use fall-through intentionally in switch (variation 140)

Level: Advanced
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-141 — Replace a 3-branch if-else-if with switch (variation 141)

Level: Advanced
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-142 — Replace a switch with object lookup (variation 142)

Level: Advanced
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-143 — Convert nested ternary to if-else (variation 143)

Level: Advanced
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-144 — Use guard clauses to flatten nested ifs (variation 144)

Level: Advanced
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-145 — Replace || default with ?? for numeric values (variation 145)

Level: Advanced
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-146 — Convert if-else to ternary for assignment (variation 146)

Level: Advanced
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-147 — Use && for conditional execution (variation 147)

Level: Advanced
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-148 — Design a state machine with switch (variation 148)

Level: Advanced
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-149 — Validate form inputs with if-else-if chain (variation 149)

Level: Advanced
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-150 — Use fall-through intentionally in switch (variation 150)

Level: Advanced
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-151 — Replace a 3-branch if-else-if with switch (variation 151)

Level: Advanced
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-152 — Replace a switch with object lookup (variation 152)

Level: Advanced
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-153 — Convert nested ternary to if-else (variation 153)

Level: Advanced
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-154 — Use guard clauses to flatten nested ifs (variation 154)

Level: Advanced
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-155 — Replace || default with ?? for numeric values (variation 155)

Level: Advanced
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-156 — Convert if-else to ternary for assignment (variation 156)

Level: Advanced
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-157 — Use && for conditional execution (variation 157)

Level: Advanced
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-158 — Design a state machine with switch (variation 158)

Level: Advanced
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-159 — Validate form inputs with if-else-if chain (variation 159)

Level: Advanced
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-160 — Use fall-through intentionally in switch (variation 160)

Level: Advanced
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-161 — Replace a 3-branch if-else-if with switch (variation 161)

Level: Advanced
When to apply: When comparing one variable to constants
Key tip: Check if all branches test the same variable
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-162 — Replace a switch with object lookup (variation 162)

Level: Advanced
When to apply: When each case returns a value
Key tip: Ensure default handling
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-163 — Convert nested ternary to if-else (variation 163)

Level: Advanced
When to apply: When nesting exceeds one level
Key tip: Readability over cleverness
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-164 — Use guard clauses to flatten nested ifs (variation 164)

Level: Advanced
When to apply: When each condition is a validation
Key tip: Return early for invalid cases
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-165 — Replace || default with ?? for numeric values (variation 165)

Level: Advanced
When to apply: When 0 is a valid value
Key tip: 0 || 10 gives 10 but 0 ?? 10 gives 0
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-166 — Convert if-else to ternary for assignment (variation 166)

Level: Advanced
When to apply: When the only difference is the assigned value
Key tip: Keep it simple, no side effects in branches
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-167 — Use && for conditional execution (variation 167)

Level: Advanced
When to apply: When you want to call a function only if truthy
Key tip: Avoid side effects in conditions
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-168 — Design a state machine with switch (variation 168)

Level: Advanced
When to apply: Finite states with defined transitions
Key tip: Handle unknown states in default
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-169 — Validate form inputs with if-else-if chain (variation 169)

Level: Advanced
When to apply: Check required, format, length, range in order
Key tip: Return first error found
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.

7.1b-170 — Use fall-through intentionally in switch (variation 170)

Level: Advanced
When to apply: Group cases that share the same handler
Key tip: Document with a comment
JS code pattern: Write a function demonstrating this refactoring.
C++ equivalent: Apply the same transformation with C++ syntax.
Interview angle: Explain why one form is preferable over another in a given context.