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. If newTarget is not present, it is target.

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

See also

• Reflect
• new
• new.target