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es-toolkit

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A state-of-the-art, high-performance JavaScript utility library with a small bundle size and strong type annotations.

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const IS_UNSIGNED_INTEGER = /^(?:0|[1-9]\d*)$/; function isIndex(value, length = Number.MAX_SAFE_INTEGER) { switch (typeof value) { case 'number': { return Number.isInteger(value) && value >= 0 && value < length; } case 'symbol': { return false; } case 'string': { return IS_UNSIGNED_INTEGER.test(value); } } } export { isIndex };