| 1 | /** Used as references for various `Number` constants. */
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| 2 | var MAX_SAFE_INTEGER = 9007199254740991;
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| 3 |
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| 4 | /** Used to detect unsigned integer values. */
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| 5 | var reIsUint = /^(?:0|[1-9]\d*)$/;
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| 6 |
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| 7 | /**
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| 8 | * Checks if `value` is a valid array-like index.
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| 9 | *
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| 10 | * @private
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| 11 | * @param {*} value The value to check.
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| 12 | * @param {number} [length=MAX_SAFE_INTEGER] The upper bounds of a valid index.
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| 13 | * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
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| 14 | */
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| 15 | function isIndex(value, length) {
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| 16 | length = length == null ? MAX_SAFE_INTEGER : length;
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| 17 | return !!length &&
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| 18 | (typeof value == 'number' || reIsUint.test(value)) &&
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| 19 | (value > -1 && value % 1 == 0 && value < length);
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| 20 | }
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| 21 |
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| 22 | module.exports = isIndex;
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