blob: 4cd82d8256c41ee0ca13c30152f6050265931e59 [file] [log] [blame]
/**
* 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;
/**
* Gets the last element or last `n` elements of an array. If a callback is
* provided elements at the end 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 _
* @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 last element(s) of `array`.
* @example
*
* _.last([1, 2, 3]);
* // => 3
*
* _.last([1, 2, 3], 2);
* // => [2, 3]
*
* _.last([1, 2, 3], function(num) {
* return num > 1;
* });
* // => [2, 3]
*
* var characters = [
* { 'name': 'barney', 'blocked': false, 'employer': 'slate' },
* { 'name': 'fred', 'blocked': true, 'employer': 'slate' },
* { 'name': 'pebbles', 'blocked': true, 'employer': 'na' }
* ];
*
* // using "_.pluck" callback shorthand
* _.pluck(_.last(characters, 'blocked'), 'name');
* // => ['fred', 'pebbles']
*
* // using "_.where" callback shorthand
* _.last(characters, { 'employer': 'na' });
* // => [{ 'name': 'pebbles', 'blocked': true, 'employer': 'na' }]
*/
function last(array, callback, thisArg) {
var n = 0,
length = array ? array.length : 0;
if (typeof callback != 'number' && callback != null) {
var index = length;
callback = createCallback(callback, thisArg, 3);
while (index-- && callback(array[index], index, array)) {
n++;
}
} else {
n = callback;
if (n == null || thisArg) {
return array ? array[length - 1] : undefined;
}
}
return slice(array, nativeMax(0, length - n));
}
module.exports = last;