Add Array.from() support to prefer-set-size rule#2857
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sindresorhus merged 3 commits intosindresorhus:mainfrom Feb 10, 2026
Merged
Add Array.from() support to prefer-set-size rule#2857sindresorhus merged 3 commits intosindresorhus:mainfrom
Array.from() support to prefer-set-size rule#2857sindresorhus merged 3 commits intosindresorhus:mainfrom
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Detect `Array.from(set).length` and suggest `set.size` instead, matching the existing behavior for `[...set].length`. Fixes sindresorhus#2843 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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sindresorhus
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Fixes #2843
The
prefer-set-sizerule now also detectsArray.from(set).lengthand suggestsset.sizeinstead, matching the existing behavior for[...set].length.Changes
Rule (
rules/prefer-set-size.js):Array.from(set).lengthwheresetis eithernew Set(...)directly or aconstvariable initialized tonew Set(...)Array.fromhas a second argument (mapping function), uses optional chaining, or the argument is not a SetArray.from(set).lengthwithset.size, suppressing the fix when comments would be lostTests (
test/prefer-set-size.js):Array.fromedge cases (wrong object, optional chaining, second argument, non-Set types, non-const variables)new Set, const variable reference, nested parentheses, outer parentheses, and comment handling