mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-23 06:10:02 +08:00
Chris Tate
c48a21b9ef
- Object.create(null) is a real null-prototype dictionary: inspect, toString, and deepStrictEqual answer Node's forms; the dynamic tier routes to the engine's own Object.create for live delegation - Object prototypes fence by name in static builds — an own-copy stance is observably wrong under Node's empty-own-set answers and live proto mutations - entries() and keys() walk any static array live in for-of heads and iterator-helper chains - Object.assign(target, ...sources) packs spreads with JS's evaluation order before any copy, with V8's position-dependent error texts # Conflicts: # packages/compiler/test/ts7/baselines/order-parity.json # packages/runtime/src/scr_json.c
57 lines
1.9 KiB
TypeScript
57 lines
1.9 KiB
TypeScript
// arr.entries()/arr.keys() consumed directly by a for-of head — the
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// dominant formatter idiom (`for (const [index, line] of
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// rawLineContents.entries())`): the LIVE index walk, exactly the array
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// iterator's contract — the length re-reads every pass, so elements
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// appended mid-walk are visited and a shrink ends the loop early.
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// `[i, v]` heads of plain identifiers bind straight from the reads (the
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// pair tuple never materializes); identifier heads bind the checker's
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// own [number, T] tuple; holes, object patterns, defaults, `let`, and
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// `var` heads ride the ordinary binding desugars. Node is the oracle
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// byte-for-byte.
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const words: string[] = ["alpha", "beta", "gamma"];
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for (const [i, w] of words.entries()) {
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console.log(i, w);
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}
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// Index-only heads, and keys() as the index iterator.
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const nums = [10, 20, 30];
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for (const [i] of nums.entries()) console.log("i", i);
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for (const k of nums.keys()) console.log("k", k);
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// An identifier head binds the [number, T] pair tuple itself.
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for (const pair of words.entries()) {
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console.log(pair[0], pair.length, pair[1]);
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}
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// Holes and object patterns over the pair.
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for (const [, w] of words.entries()) console.log("w", w);
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for (const { 0: idx, 1: word } of words.entries()) console.log(idx, word);
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// Number elements through arithmetic — index times value.
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let sum = 0;
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for (const [i, n] of nums.entries()) sum += i * n;
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console.log(sum);
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// LIVE iteration: appends made mid-walk are visited (the length
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// re-reads), and break exits normally.
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const live = ["a"];
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for (const [i, v] of live.entries()) {
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if (i < 2) live.push(v + "!");
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console.log(i, v);
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if (i > 3) break;
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}
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console.log(live.length);
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// let heads reassign their per-iteration binding; var heads share one
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// hoisted slot that persists after the loop.
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for (let [i, w] of words.entries()) {
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i += 1;
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console.log(i, w);
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}
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for (var [vi, vw] of words.entries()) {
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if (vi === 2) break;
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}
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console.log("after", vi!, vw!);
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console.log("done");
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