JavaScript Instanceof Operator

The instanceof operator in JavaScript is used to check the type of an object at run time. It returns a boolean value if true then it indicates that the object is an instance of a particular class and if false then it is not. 

Syntax:

var gfg = objectName instanceof objectType

Parameters: This method accepts a single parameter.

• objectName: States the name of the Object.

Return Value: This method returns a boolean value if true then it indicates that the object is an instance of a particular class and if false then it is not. 

Example 1: Below is the example of the Instanceof Operator.

html

<h1 style="color:green">
    GeeksforGeeks
</h1>
<h3>
    Instanceof Operator.
</h3>

<p id="GFG"></p>

<script>
    var a = ["Geeks", "for", "Geeks"];

    document.getElementById("GFG").innerHTML =
        (a instanceof Array) + "<br>" +
        (a instanceof Number);
</script>

Output:

JavaScript Instanceof Operator

Example 2:

html

<h1 style="color:green">
    GeeksforGeeks
</h1>
<h3>
    Instanceof Operator.
</h3>

<p id="GFG"></p>

<script>
    var fruits = ["Apple", "Mango", "Banana"];

    document.getElementById("GFG").innerHTML =
        (fruits instanceof Array) + "<br>" +
        (fruits instanceof Object) + "<br>" +
        (fruits instanceof String) + "<br>" +
        (fruits instanceof Number);
</script>

Output:

JavaScript Instanceof Operator

Example 3: Demonstrating that String and Date objects are also a type of Object (derived from Object). 

Javascript

<script>
    var myString = new String();
    var myDate = new Date();

    console.log(myString instanceof Object);
    console.log(myString instanceof Date);
    console.log(myString instanceof String);
    console.log(myDate instanceof Date);
    console.log(myDate instanceof Object);
    console.log(myDate instanceof String);
</script>

Output:

true
false
true
true
true
false

We have a complete list of Javascript Operators, to check those please go through the Javascript Operators Complete Reference article.

Supported Browsers:

• Google Chrome
• Firefox
• Edge
• Opera
• Apple Safari