var baseIndexOf = require('../internal/baseIndexOf'), binaryIndex = require('../internal/binaryIndex'); /* Native method references for those with the same name as other `lodash` methods. */ var nativeMax = Math.max; /** * Gets the index at which the first occurrence of `value` is found in `array` * using `SameValueZero` for equality comparisons. If `fromIndex` is negative, * it is used as the offset from the end of `array`. If `array` is sorted * providing `true` for `fromIndex` performs a faster binary search. * * **Note:** [`SameValueZero`](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-samevaluezero) * comparisons are like strict equality comparisons, e.g. `===`, except that * `NaN` matches `NaN`. * * @static * @memberOf _ * @category Array * @param {Array} array The array to search. * @param {*} value The value to search for. * @param {boolean|number} [fromIndex=0] The index to search from or `true` * to perform a binary search on a sorted array. * @returns {number} Returns the index of the matched value, else `-1`. * @example * * _.indexOf([1, 2, 1, 2], 2); * // => 1 * * // using `fromIndex` * _.indexOf([1, 2, 1, 2], 2, 2); * // => 3 * * // performing a binary search * _.indexOf([1, 1, 2, 2], 2, true); * // => 2 */ function indexOf(array, value, fromIndex) { var length = array ? array.length : 0; if (!length) { return -1; } if (typeof fromIndex == 'number') { fromIndex = fromIndex < 0 ? nativeMax(length + fromIndex, 0) : fromIndex; } else if (fromIndex) { var index = binaryIndex(array, value), other = array[index]; if (value === value ? (value === other) : (other !== other)) { return index; } return -1; } return baseIndexOf(array, value, fromIndex || 0); } module.exports = indexOf;