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 | var type = typeof value;
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17 | length = length == null ? MAX_SAFE_INTEGER : length;
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18 |
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19 | return !!length &&
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20 | (type == 'number' ||
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21 | (type != 'symbol' && reIsUint.test(value))) &&
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22 | (value > -1 && value % 1 == 0 && value < length);
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23 | }
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24 |
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25 | module.exports = isIndex;
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