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(target, argumentsList, newTarget)

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

• target: This parameter is the target function that is going to be called.
• ArgumentsList: This parameter is an array-like object specifying the argument with which the target should be called.
• newTarget: 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.

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

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

javascript

<script>
    function func1(a, b, c) {
      this.sum = a + b + c;
    }

    const args = [1, 2, 3];
    const object1 = new func1(...args);
    const object2 = Reflect.construct(func1, args);

    console.log(object2.sum);

    console.log(object1.sum);

    function func2(a, b, c) {
      this.sum = a + b + c;
    }
    const args2 = [1, 4, 3];
    const args3 = [1, 2, 3];
    const object3 = new func1(...args);
    const object4 = Reflect.construct(func2, args2);
    console.log(object4.sum);
    console.log(object3.sum);
</script>

Output:

6
6
8
6

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

javascript

<script>
    function OneClass() {
        this.name = 'one'
    }

    function OtherClass() {
        this.name = 'other'
    }
    const args=[1, 2, 3];

    let obj1 = Reflect.construct(OneClass, args, OtherClass)

    let obj2 = Object.create(OtherClass.prototype)
    OneClass.apply(obj2, args)

    console.log(obj1.name)
    console.log(obj2.name)

    console.log(obj1 instanceof OneClass)
    console.log(obj2 instanceof OneClass)

    console.log(obj1 instanceof OtherClass)
    console.log(obj2 instanceof OtherClass)
</script>

Output:

"one"
"one"
false
false
true
true

Supported Browsers: The browsers supported by JavaScript Reflect.apply() Method 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.