function-bind.js
No OneTemporary
Actions

Size

1 KB

Subscribers

None

function-bind.js
View Options

	'use strict';
	var uncurryThis = require('../internals/function-uncurry-this');
	var aCallable = require('../internals/a-callable');
	var isObject = require('../internals/is-object');
	var hasOwn = require('../internals/has-own-property');
	var arraySlice = require('../internals/array-slice');
	var NATIVE_BIND = require('../internals/function-bind-native');

	var $Function = Function;
	var concat = uncurryThis([].concat);
	var join = uncurryThis([].join);
	var factories = {};

	var construct = function (C, argsLength, args) {
	if (!hasOwn(factories, argsLength)) {
	for (var list = [], i = 0; i < argsLength; i++) list[i] = 'a[' + i + ']';
	factories[argsLength] = $Function('C,a', 'return new C(' + join(list, ',') + ')');
	} return factories[argsLength](C, args);
	};

	// `Function.prototype.bind` method implementation
	// https://tc39.es/ecma262/#sec-function.prototype.bind
	module.exports = NATIVE_BIND ? $Function.bind : function bind(that /* , ...args */) {
	var F = aCallable(this);
	var Prototype = F.prototype;
	var partArgs = arraySlice(arguments, 1);
	var boundFunction = function bound(/* args... */) {
	var args = concat(partArgs, arraySlice(arguments));
	return this instanceof boundFunction ? construct(F, args.length, args) : F.apply(that, args);
	};
	if (isObject(Prototype)) boundFunction.prototype = Prototype;
	return boundFunction;
	};