28 lines
1.0 KiB
JavaScript
28 lines
1.0 KiB
JavaScript
'use strict';
|
|
var aFunction = require('../internals/a-function');
|
|
var isObject = require('../internals/is-object');
|
|
|
|
var slice = [].slice;
|
|
var factories = {};
|
|
|
|
var construct = function (C, argsLength, args) {
|
|
if (!(argsLength in factories)) {
|
|
for (var list = [], i = 0; i < argsLength; i++) list[i] = 'a[' + i + ']';
|
|
// eslint-disable-next-line no-new-func
|
|
factories[argsLength] = Function('C,a', 'return new C(' + list.join(',') + ')');
|
|
} return factories[argsLength](C, args);
|
|
};
|
|
|
|
// `Function.prototype.bind` method implementation
|
|
// https://tc39.github.io/ecma262/#sec-function.prototype.bind
|
|
module.exports = Function.bind || function bind(that /* , ...args */) {
|
|
var fn = aFunction(this);
|
|
var partArgs = slice.call(arguments, 1);
|
|
var boundFunction = function bound(/* args... */) {
|
|
var args = partArgs.concat(slice.call(arguments));
|
|
return this instanceof boundFunction ? construct(fn, args.length, args) : fn.apply(that, args);
|
|
};
|
|
if (isObject(fn.prototype)) boundFunction.prototype = fn.prototype;
|
|
return boundFunction;
|
|
};
|