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61 lines
1.6 KiB
JavaScript
61 lines
1.6 KiB
JavaScript
var binaryIndex = require('../internal/binaryIndex'),
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indexOfNaN = require('../internal/indexOfNaN');
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/* Native method references for those with the same name as other `lodash` methods. */
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var nativeMax = Math.max,
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nativeMin = Math.min;
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/**
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* This method is like `_.indexOf` except that it iterates over elements of
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* `array` from right to left.
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*
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* @static
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* @memberOf _
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* @category Array
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* @param {Array} array The array to search.
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* @param {*} value The value to search for.
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* @param {boolean|number} [fromIndex=array.length-1] The index to search from
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* or `true` to perform a binary search on a sorted array.
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* @returns {number} Returns the index of the matched value, else `-1`.
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* @example
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*
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* _.lastIndexOf([1, 2, 1, 2], 2);
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* // => 3
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*
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* // using `fromIndex`
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* _.lastIndexOf([1, 2, 1, 2], 2, 2);
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* // => 1
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*
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* // performing a binary search
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* _.lastIndexOf([1, 1, 2, 2], 2, true);
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* // => 3
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*/
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function lastIndexOf(array, value, fromIndex) {
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var length = array ? array.length : 0;
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if (!length) {
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return -1;
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}
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var index = length;
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if (typeof fromIndex == 'number') {
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index = (fromIndex < 0 ? nativeMax(length + fromIndex, 0) : nativeMin(fromIndex || 0, length - 1)) + 1;
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} else if (fromIndex) {
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index = binaryIndex(array, value, true) - 1;
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var other = array[index];
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if (value === value ? (value === other) : (other !== other)) {
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return index;
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}
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return -1;
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}
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if (value !== value) {
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return indexOfNaN(array, index, true);
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}
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while (index--) {
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if (array[index] === value) {
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return index;
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}
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}
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return -1;
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}
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module.exports = lastIndexOf;
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