Why does this JavaScript Object is vs === for NaN?
Why does this JavaScript Object is vs === for NaN check. The JavaScript code uses === to detect NaN. In JavaScript Object.is is needed for NaN and negative zero.
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Why does this JavaScript WeakMap key garbage collected?
Why does this JavaScript WeakMap key garbage collected too early. The JavaScript code stores data in WeakMap keyed by object. In JavaScript without a strong reference the entry disappears.
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Why does this JavaScript Object keys on array?
Why does this JavaScript Object keys on array returning string indices. The JavaScript code uses Object.keys on an array. In JavaScript keys are string numbers and holes are skipped.
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Why does this JavaScript substring vs substr deprecated?
Why does this JavaScript substring vs substr giving different results. The JavaScript code uses substr which is deprecated and has different semantics. In JavaScript substr start and length vs substring start and end.
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Why does this JavaScript Array from object returning wrong?
Why does this JavaScript Array from object returning wrong length. The JavaScript code creates array from array-like using length. In JavaScript a malicious length can allocate huge or wrong size.
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What's wrong with this JavaScript Array push return?
What's wrong with this JavaScript Array push return in a chain. The JavaScript code chains after push assuming it returns the array. In JavaScript push returns the new length not the array.
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What's wrong with this JavaScript setTimeout closure?
What's wrong with this JavaScript setTimeout closure in a loop. The JavaScript code creates timeouts in a loop with var. In JavaScript all callbacks see the final value.
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What's wrong with this JavaScript default parameter evaluation?
What's wrong with this JavaScript default parameter evaluation timing. The JavaScript code uses an expression as default. In JavaScript defaults are evaluated at call time and can have side effects.
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What's wrong with this JavaScript cache data?
What's wrong with this JavaScript cache data in a response handler. The JavaScript code caches a mutable array and returns it directly, so callers mutate shared state. In JavaScript services this causes ghost data.
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What's wrong with this JavaScript Map for object keys?
What's wrong with this JavaScript Map for object keys with reference equality. The JavaScript code uses objects as Map keys. In JavaScript key lookup uses reference so same-shaped objects do not match.
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