Instanceof operator in JavaScript

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:
objectName: States the name of Object.



Example-1: objectTypes.

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<!DOCTYPE html>
<html>
  
<body>
    <center>
        <h1 style="color:green">GeeksforGeeks</h1>
  
        <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>
    </center>
</body>
  
</html>

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Output:

Example-2: Demonstrating that String and Date objects are also a type of Object (derived from Object).

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<!DOCTYPE html>
<html>
  
<body>
    <h1 style="color:green">GeeksforGeeks</h1>
  
    <p id="GFG"></p>
  
    <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>
</body>
  
</html>

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Output

Supported Browsers:

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


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