JavaScript Reflect construct() Method

JavaScript Reflect.construct() method in JavaScript is used to call a new target. It gives also the added option to specify a different prototype.

Syntax:

Reflect.construct(para1, para2, para3)

Parameters: This method accepts three parameters as mentioned above and described below:

• para1: This parameter is the target function that is going to be called.
• para2: This parameter is an array-like object specifying the argument with which the target should be called.
• para3: It is an optional parameter. The constructor whose prototype should be used.

Return Value: This method returns a new instance of the target.

Exceptions: A TypeError is an exception given as the result when the target is not a constructor.

The below examples illustrate the Reflect.construct() method in JavaScript:

Example 1: This example shows the basic use of the Reflect.construct() method in JavaScript.

function addNumbers(x, y, z) {
    this.sum = x + y + z;
}

const values1 = [1, 2, 3];
const obj1 = new addNumbers(...values1);
const obj2 = Reflect.construct(addNumbers, values1);

console.log(obj2.sum);
console.log(obj1.sum);

function calculateSum(p, q, r) {
    this.sum = p + q + r;
}

const values2 = [1, 4, 3];
const values3 = [1, 2, 3];
const obj3 = new addNumbers(...values3);
const obj4 = Reflect.construct(calculateSum, values2);
console.log(obj4.sum);
console.log(obj3.sum);

6
6
8
6

Example 2: This example shows the basic use of the Reflect.construct() method in JavaScript.

class FirstClass {
    constructor(name) {
        this.name = name;
    }
}

class SecondClass {
    constructor(name) {
        this.name = name;
    }
}

const values = ['one'];

let objA = new FirstClass(...values);

let objB = new SecondClass(...values);

console.log(objA.name);
console.log(objB.name);

console.log(objA instanceof FirstClass);
console.log(objB instanceof FirstClass);

console.log(objA instanceof SecondClass);
console.log(objB instanceof SecondClass);

one
one
true
false
false
true

Supported Browsers:

The browsers are supported by JavaScript Reflect.apply() Methods are listed below:

• Google Chrome 49 and above
• Edge 12 and above
• Firefox 42 and above
• Opera 36 and above
• Safari 10 and above

We have a complete list of Javascript Reflects methods, to check those go through the JavaScript Reflect Reference article.