JavaScript Array isArray() Method

The isArray() method in JavaScript is used to determine whether a given value is an array or not. This method returns true if the argument passed is an array else it returns false.

Syntax:

Array.isArray(obj);

Parameters:

• obj: This parameter holds the object that will be tested.

Return value:

This function returns the Boolean value true if the argument passed is an array otherwise it returns false. 

Example 1: Checking if a Value is an Array using Array.isArray()

The code defines a function func() checking if 'foobar' is an array using Array.isArray(). It logs false. 'foobar' isn't an array, confirming the method's accuracy.

// JavaScript code for isArray() function
function func() {
    console.log(Array.isArray('foobar'));
}

func();

false

Example 2: Passing map in isArray() Method

Since the argument passed to the function isArray() is a map therefore this function returns false as the answer.

// JavaScript code for isArray() function
function func() {
    console.log(Array.isArray({ foo: 123 }));
}
func();

false

Example 3: Illustration of Array.isArray() Method on nested Array.

// Array.isArray() method on 1D Array
const arr=[1,2,3,4,5,7,6];
const result=Array.isArray(arr)
console.log(result);


//Array.isArray()   method on nested Array
const num = [1, [4, 9, 16], 25];
const sqRoot = num.map(num => {
    if (Array.isArray(num)) 
    {
        //to iterate over the nested array
        return num.map(innerNum => Math.sqrt(innerNum));
    } else
    {
        return Math.sqrt(num);
    }
});

console.log(sqRoot); // Output: [1, [2, 3, 4], 5]

true
[ 1, [ 2, 3, 4 ], 5 ]

We have a complete list of Javascript Array methods, to check those please go through this Javascript Array Complete reference article.

Supported Browsers:

• Google Chrome 5.0
• Microsoft Edge 12
• Mozilla Firefox 4.0
• Safari 5.0
• Opera 10.5