2 var global = require('../internals/global');
3 var uncurryThis = require('../internals/function-uncurry-this');
4 var aCallable = require('../internals/a-callable');
5 var isObject = require('../internals/is-object');
6 var hasOwn = require('../internals/has-own-property');
7 var arraySlice = require('../internals/array-slice');
9 var Function = global.Function;
10 var concat = uncurryThis([].concat);
11 var join = uncurryThis([].join);
14 var construct = function (C, argsLength, args) {
15 if (!hasOwn(factories, argsLength)) {
16 for (var list = [], i = 0; i < argsLength; i++) list[i] = 'a[' + i + ']';
17 factories[argsLength] = Function('C,a', 'return new C(' + join(list, ',') + ')');
18 } return factories[argsLength](C, args);
21 // `Function.prototype.bind` method implementation
22 // https://tc39.es/ecma262/#sec-function.prototype.bind
23 module.exports = Function.bind || function bind(that /* , ...args */) {
24 var F = aCallable(this);
25 var Prototype = F.prototype;
26 var partArgs = arraySlice(arguments, 1);
27 var boundFunction = function bound(/* args... */) {
28 var args = concat(partArgs, arraySlice(arguments));
29 return this instanceof boundFunction ? construct(F, args.length, args) : F.apply(that, args);
31 if (isObject(Prototype)) boundFunction.prototype = Prototype;