UNPKG

1.73 kBJavaScriptView Raw
1import apply from './_apply.js';
2import arrayPush from './_arrayPush.js';
3import baseRest from './_baseRest.js';
4import castSlice from './_castSlice.js';
5import toInteger from './toInteger.js';
6
7/** Error message constants. */
8var FUNC_ERROR_TEXT = 'Expected a function';
9
10/* Built-in method references for those with the same name as other `lodash` methods. */
11var nativeMax = Math.max;
12
13/**
14 * Creates a function that invokes `func` with the `this` binding of the
15 * create function and an array of arguments much like
16 * [`Function#apply`](http://www.ecma-international.org/ecma-262/7.0/#sec-function.prototype.apply).
17 *
18 * **Note:** This method is based on the
19 * [spread operator](https://mdn.io/spread_operator).
20 *
21 * @static
22 * @memberOf _
23 * @since 3.2.0
24 * @category Function
25 * @param {Function} func The function to spread arguments over.
26 * @param {number} [start=0] The start position of the spread.
27 * @returns {Function} Returns the new function.
28 * @example
29 *
30 * var say = _.spread(function(who, what) {
31 * return who + ' says ' + what;
32 * });
33 *
34 * say(['fred', 'hello']);
35 * // => 'fred says hello'
36 *
37 * var numbers = Promise.all([
38 * Promise.resolve(40),
39 * Promise.resolve(36)
40 * ]);
41 *
42 * numbers.then(_.spread(function(x, y) {
43 * return x + y;
44 * }));
45 * // => a Promise of 76
46 */
47function spread(func, start) {
48 if (typeof func != 'function') {
49 throw new TypeError(FUNC_ERROR_TEXT);
50 }
51 start = start == null ? 0 : nativeMax(toInteger(start), 0);
52 return baseRest(function(args) {
53 var array = args[start],
54 otherArgs = castSlice(args, 0, start);
55
56 if (array) {
57 arrayPush(otherArgs, array);
58 }
59 return apply(func, this, otherArgs);
60 });
61}
62
63export default spread;