1.17 — Additional Topics: Quick Revision

Episode 1 supplement — print-friendly.

How to use

Skim → drill weak spots in 1.17.a / 1.17.b → 1.17-Exercise-Questions.md.

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Throttle vs debounce

	Throttle	Debounce
Idea	Max 1 call per wait ms while firing	Run after delay ms quiet`
Examples	Scroll spy, sampled metrics	Search-as-you-type, resize-end layout
Timer	Last-run timestamp (typical)	setTimeout reset each call

Scroll performance: combine with { passive: true } when not calling preventDefault.

Visual sync: consider requestAnimationFrame.

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JSON (Episode 1 scope)

JSON.stringify({ a: 1 });           // '{"a":1}'
JSON.parse('{"a":1}');              // { a: 1 }

localStorage.setItem("k", JSON.stringify(obj));
JSON.parse(localStorage.getItem("k") ?? "{}");

API	Role
JSON.stringify(value)	Value → string (throws on cycle)
JSON.parse(text)	Valid JSON string → value (SyntaxError if bad)
response.json()	fetch helper — parse body as JSON

Not in JSON: functions, undefined (dropped in objects), Symbol keys, arbitrary class types (plain objects round-trip).

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One-liners

• Throttle = cap frequency.
• Debounce = wait for silence.
• parse/stringify = bridge objects ↔ text for HTTP and storage.

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End of 1.17 quick revision.