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conformance · v153
v153 · joint-iteration — conformance probe
8 assertions drawn from the spec. Each is a single contract the spec text makes. Pass/fail reflects what this browser executed; blocked means the contract was not run because it needs user mediation, hardware, or another unavailable precondition. Open the page in Chrome stable / canary / Firefox / Safari to compare.
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| id | contract | kind | verdict | detail |
|---|---|---|---|---|
iterator-constructor-exists |
Both methods are statics on the Iterator constructor, so its presence is the precondition for the feature. spec ↗ | typeof | … | |
iterator-zip-exists |
The positional form: an iterable of iterables in, an iterator of arrays out. spec ↗ | script | … | |
iterator-zipkeyed-exists |
The keyed form: an object of iterables in, an iterator of objects out. spec ↗ | script | … | |
zip-defaults-to-shortest |
With no options at all, ragged sources truncate to the shortest rather than padding or throwing. A default that padded would silently produce undefined values in every existing call site. spec ↗ | script | … | |
zip-rejects-an-unknown-mode |
An unrecognised mode is a TypeError, not a silent fallback to the default. This is the difference between a typo you find immediately and one that ships. spec ↗ | script | … | |
zip-longest-substitutes-padding |
Under longest, a source that has finished contributes its padding entry for every remaining step, and the walk continues until the last source is spent. spec ↗ | script | … | |
zip-strict-throws-at-the-diverging-step |
Strict cannot pre-check lengths — an iterator has none — so it yields until the step where the sources stop agreeing and throws there. Two values arrive before the TypeError, which is exactly why a strict consumer must treat the throw as fatal rather than keeping what it already read. spec ↗ | script | … | |
zip-closes-abandoned-iterators |
The core cleanup guarantee, and the thing hand-rolled zips get wrong: when the walk ends early, the sources still open must be closed, so a generator's finally block runs instead of waiting on the collector. spec ↗ | script | … |