1 // 26.1.2 Reflect.construct(target, argumentsList [, newTarget])
2 var $export = require('./_export')
3 , create = require('./_object-create')
4 , aFunction = require('./_a-function')
5 , anObject = require('./_an-object')
6 , isObject = require('./_is-object')
7 , fails = require('./_fails')
8 , bind = require('./_bind')
9 , rConstruct = (require('./_global').Reflect || {}).construct;
11 // MS Edge supports only 2 arguments and argumentsList argument is optional
12 // FF Nightly sets third argument as `new.target`, but does not create `this` from it
13 var NEW_TARGET_BUG = fails(function(){
15 return !(rConstruct(function(){}, [], F) instanceof F);
17 var ARGS_BUG = !fails(function(){
18 rConstruct(function(){});
21 $export($export.S + $export.F * (NEW_TARGET_BUG || ARGS_BUG), 'Reflect', {
22 construct: function construct(Target, args /*, newTarget*/){
25 var newTarget = arguments.length < 3 ? Target : aFunction(arguments[2]);
26 if(ARGS_BUG && !NEW_TARGET_BUG)return rConstruct(Target, args, newTarget);
27 if(Target == newTarget){
28 // w/o altered newTarget, optimization for 0-4 arguments
30 case 0: return new Target;
31 case 1: return new Target(args[0]);
32 case 2: return new Target(args[0], args[1]);
33 case 3: return new Target(args[0], args[1], args[2]);
34 case 4: return new Target(args[0], args[1], args[2], args[3]);
36 // w/o altered newTarget, lot of arguments case
38 $args.push.apply($args, args);
39 return new (bind.apply(Target, $args));
41 // with altered newTarget, not support built-in constructors
42 var proto = newTarget.prototype
43 , instance = create(isObject(proto) ? proto : Object.prototype)
44 , result = Function.apply.call(Target, instance, args);
45 return isObject(result) ? result : instance;