| /** |
| * Lo-Dash 2.4.1 (Custom Build) <http://lodash.com/> |
| * Build: `lodash modularize modern exports="node" -o ./modern/` |
| * Copyright 2012-2013 The Dojo Foundation <http://dojofoundation.org/> |
| * Based on Underscore.js 1.5.2 <http://underscorejs.org/LICENSE> |
| * Copyright 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors |
| * Available under MIT license <http://lodash.com/license> |
| */ |
| var createCallback = require('../functions/createCallback'), |
| slice = require('../internals/slice'); |
| |
| /* Native method shortcuts for methods with the same name as other `lodash` methods */ |
| var nativeMax = Math.max, |
| nativeMin = Math.min; |
| |
| /** |
| * Gets the first element or first `n` elements of an array. If a callback |
| * is provided elements at the beginning of the array are returned as long |
| * as the callback returns truey. The callback is bound to `thisArg` and |
| * invoked with three arguments; (value, index, array). |
| * |
| * If a property name is provided for `callback` the created "_.pluck" style |
| * callback will return the property value of the given element. |
| * |
| * If an object is provided for `callback` the created "_.where" style callback |
| * will return `true` for elements that have the properties of the given object, |
| * else `false`. |
| * |
| * @static |
| * @memberOf _ |
| * @alias head, take |
| * @category Arrays |
| * @param {Array} array The array to query. |
| * @param {Function|Object|number|string} [callback] The function called |
| * per element or the number of elements to return. If a property name or |
| * object is provided it will be used to create a "_.pluck" or "_.where" |
| * style callback, respectively. |
| * @param {*} [thisArg] The `this` binding of `callback`. |
| * @returns {*} Returns the first element(s) of `array`. |
| * @example |
| * |
| * _.first([1, 2, 3]); |
| * // => 1 |
| * |
| * _.first([1, 2, 3], 2); |
| * // => [1, 2] |
| * |
| * _.first([1, 2, 3], function(num) { |
| * return num < 3; |
| * }); |
| * // => [1, 2] |
| * |
| * var characters = [ |
| * { 'name': 'barney', 'blocked': true, 'employer': 'slate' }, |
| * { 'name': 'fred', 'blocked': false, 'employer': 'slate' }, |
| * { 'name': 'pebbles', 'blocked': true, 'employer': 'na' } |
| * ]; |
| * |
| * // using "_.pluck" callback shorthand |
| * _.first(characters, 'blocked'); |
| * // => [{ 'name': 'barney', 'blocked': true, 'employer': 'slate' }] |
| * |
| * // using "_.where" callback shorthand |
| * _.pluck(_.first(characters, { 'employer': 'slate' }), 'name'); |
| * // => ['barney', 'fred'] |
| */ |
| function first(array, callback, thisArg) { |
| var n = 0, |
| length = array ? array.length : 0; |
| |
| if (typeof callback != 'number' && callback != null) { |
| var index = -1; |
| callback = createCallback(callback, thisArg, 3); |
| while (++index < length && callback(array[index], index, array)) { |
| n++; |
| } |
| } else { |
| n = callback; |
| if (n == null || thisArg) { |
| return array ? array[0] : undefined; |
| } |
| } |
| return slice(array, 0, nativeMin(nativeMax(0, n), length)); |
| } |
| |
| module.exports = first; |