JavaScript Reflect.construct() Method

The static Reflect.construct() method allows to invoke a constructor with a variable number of arguments. It gives also the added option to specify a different prototype.

Syntax

Parameter

target: It is the target function to call.

argumentsList: It is an array-like object specifying the arguments with which target should be called.

newTarget: It is a constructor whose prototype should be used. See also the new.target operator. If newTarget is not present, it will treat as a target.

Return

This method returns a new instance of the target (or newTarget if present), initialized by the target as a constructor with the given arguments.

Exceptions

This exception will throw a TypeError if target or newTarget are not constructors.

Example 1

const a = new Array(1,2,3);
const b = Reflect.construct ( Array, [1,2,3] );
console.log(a);
console.log(b);

Output:

 [1, 2, 3]
 [1, 2, 3]

Example 2

function func1(a, b, c) {
  this.sum = a + b + c;
}
const args = [1, 2, 3];
const object1 = new func1(...args);
console.log(object1.sum);

Output:

Example 3

function func1(a, b, c) {
  this.sum = a + b + c;
}
function func2(a, b, c) {
  this.sum = a + b + c;
}
const args2 = [1, 4, 3];
const args = [1, 2, 3];
const object1 = new func1(...args);
const object2 = Reflect.construct(func2, args2);
console.log(object2.sum);
console.log(object1.sum);

Output: