| 'use strict'; |
| var aFunction = require('./_a-function'); |
| var isObject = require('./_is-object'); |
| var invoke = require('./_invoke'); |
| var arraySlice = [].slice; |
| var factories = {}; |
| |
| var construct = function (F, len, args) { |
| if (!(len in factories)) { |
| for (var n = [], i = 0; i < len; i++) n[i] = 'a[' + i + ']'; |
| // eslint-disable-next-line no-new-func |
| factories[len] = Function('F,a', 'return new F(' + n.join(',') + ')'); |
| } return factories[len](F, args); |
| }; |
| |
| module.exports = Function.bind || function bind(that /* , ...args */) { |
| var fn = aFunction(this); |
| var partArgs = arraySlice.call(arguments, 1); |
| var bound = function (/* args... */) { |
| var args = partArgs.concat(arraySlice.call(arguments)); |
| return this instanceof bound ? construct(fn, args.length, args) : invoke(fn, args, that); |
| }; |
| if (isObject(fn.prototype)) bound.prototype = fn.prototype; |
| return bound; |
| }; |