Reflect.construct()
The static Reflect
.construct()
method acts like the new
operator as a function. It is equivalent to calling new target(...args)
.
Syntax
Reflect.construct(target, argumentsList[, newTarget])
Parameters
target
- The target function to call.
argumentsList
- An array-like object specifying the arguments with which
target
should be called. newTarget
Optional- The constructor to be used. See also the
new.target
operator. IfnewTarget
is not present, it istarget
.
Return value
A new instance of the given target, created by calling it (or newTarget
, if present) as a constructor with the given arguments.
Exceptions
A TypeError
, if target
or newTarget
are not constructors.
Description
Reflect.construct
allows you to invoke a constructor with a variable number of arguments (which would also be possible by using the spread operator combined with the new operator).
var obj = new Foo(...args); var obj = Reflect.construct(Foo, args);
Examples
Using Reflect.construct()
var d = Reflect.construct(Date, [1776, 6, 4]); d instanceof Date; // true d.getFullYear(); // 1776
Using the newTarget
parameter
See also classes for more information about sub-classing and the new.target
operator.
function someConstructor() {} var result = Reflect.construct(Array, [], someConstructor); Reflect.getPrototypeOf(result); // someConstructor.prototype Array.isArray(result); // true
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Reflect.construct' in that specification. |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Reflect.construct' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 49 | 42 (42) | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | No support | 42.0 (42) | No support | No support | No support |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/reflect/construct