| // 26.1.2 Reflect.construct(target, argumentsList [, newTarget]) |
| var $export = require('./_export') |
| , create = require('./_object-create') |
| , aFunction = require('./_a-function') |
| , anObject = require('./_an-object') |
| , isObject = require('./_is-object') |
| , bind = require('./_bind'); |
| |
| // MS Edge supports only 2 arguments |
| // FF Nightly sets third argument as `new.target`, but does not create `this` from it |
| $export($export.S + $export.F * require('./_fails')(function(){ |
| function F(){} |
| return !(Reflect.construct(function(){}, [], F) instanceof F); |
| }), 'Reflect', { |
| construct: function construct(Target, args /*, newTarget*/){ |
| aFunction(Target); |
| var newTarget = arguments.length < 3 ? Target : aFunction(arguments[2]); |
| if(Target == newTarget){ |
| // w/o altered newTarget, optimization for 0-4 arguments |
| if(args != undefined)switch(anObject(args).length){ |
| case 0: return new Target; |
| case 1: return new Target(args[0]); |
| case 2: return new Target(args[0], args[1]); |
| case 3: return new Target(args[0], args[1], args[2]); |
| case 4: return new Target(args[0], args[1], args[2], args[3]); |
| } |
| // w/o altered newTarget, lot of arguments case |
| var $args = [null]; |
| $args.push.apply($args, args); |
| return new (bind.apply(Target, $args)); |
| } |
| // with altered newTarget, not support built-in constructors |
| var proto = newTarget.prototype |
| , instance = create(isObject(proto) ? proto : Object.prototype) |
| , result = Function.apply.call(Target, instance, args); |
| return isObject(result) ? result : instance; |
| } |
| }); |