How to Check If Object is an Array in JavaScript

Use the Array.isArray() Method

You can use the JavaScript Array.isArray() method to check whether an object (or a variable) is an array or not. This method returns true if the value is an array; otherwise returns false.

Let's check out the following example to understand 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>

The Array.isArray() method is supported in all major browsers, such as Chrome, Firefox, IE (9 and above)