How to Check If Object is an Array in JavaScript

Table of Contents

JavaScript Array.isArray() can be used to determine if an object (or variable) is an array. If the value is an array, this method returns true . Otherwise, it returns false.

Let’s take a look at the following illustration to see how it works.

<script>
    // Creating some variables
    var v1 = {name: "John", age: 18};   
    var v2 = ["red", "green", "blue", "yellow"];
    var v3 = [1, 2, 3, 4, 5];
    var v4 = null;
    
    // Testing the variables data type
    typeof(v1); // Returns: "object"
    typeof(v2); // Returns: "object"
    typeof(v3); // Returns: "object"
    typeof(v3); // Returns: "object"
    
    // Testing if the variable is an array
    Array.isArray(v1);  // Returns: false
    Array.isArray(v2);  // Returns: true
    Array.isArray(v3);  // Returns: true
    Array.isArray(v4);  // Returns: false
</script>

All major browsers support the Array.isArray() method, including Chrome, Firefox, IE (9+), and others. To learn more about JavaScript arrays, see the tutorial.