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node_modules/lodash/findIndex.js 1.62 KB
aaac7fed   liuqimichale   add
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  var baseFindIndex = require('./_baseFindIndex'),
      baseIteratee = require('./_baseIteratee'),
      toInteger = require('./toInteger');
  
  /* Built-in method references for those with the same name as other `lodash` methods. */
  var nativeMax = Math.max;
  
  /**
   * This method is like `_.find` except that it returns the index of the first
   * element `predicate` returns truthy for instead of the element itself.
   *
   * @static
   * @memberOf _
   * @since 1.1.0
   * @category Array
   * @param {Array} array The array to inspect.
   * @param {Function} [predicate=_.identity] The function invoked per iteration.
   * @param {number} [fromIndex=0] The index to search from.
   * @returns {number} Returns the index of the found element, else `-1`.
   * @example
   *
   * var users = [
   *   { 'user': 'barney',  'active': false },
   *   { 'user': 'fred',    'active': false },
   *   { 'user': 'pebbles', 'active': true }
   * ];
   *
   * _.findIndex(users, function(o) { return o.user == 'barney'; });
   * // => 0
   *
   * // The `_.matches` iteratee shorthand.
   * _.findIndex(users, { 'user': 'fred', 'active': false });
   * // => 1
   *
   * // The `_.matchesProperty` iteratee shorthand.
   * _.findIndex(users, ['active', false]);
   * // => 0
   *
   * // The `_.property` iteratee shorthand.
   * _.findIndex(users, 'active');
   * // => 2
   */
  function findIndex(array, predicate, fromIndex) {
    var length = array == null ? 0 : array.length;
    if (!length) {
      return -1;
    }
    var index = fromIndex == null ? 0 : toInteger(fromIndex);
    if (index < 0) {
      index = nativeMax(length + index, 0);
    }
    return baseFindIndex(array, baseIteratee(predicate, 3), index);
  }
  
  module.exports = findIndex;