JavaScript Check if Variable is Array

When writing functions that expect an array as an argument, it’s important to check the input to make sure it matches the expected data type. If you pass the wrong data type it can lead to such errors or unexpected behavior. So you can prevent runtime errors by checking that a variable is an array before using it in array-specific functions. In this article, we’ll explore how to check if the variable is an array in javascript.

3 ways to check if variable is array

1. Using the Array.isArray() method

JavaScript provides a built-in method called Array.isArray() to check if a variable is an array. This method returns true if the provided argument is an array and false otherwise. Here’s an example of how to use it:

const myVariable = [1, 2, 3];

if (Array.isArray(myVariable)) {
  console.log('myVariable is an array');
 } else {
  console.log('myVariable is not an array');
 }

2. Using the instanceof operator:

The Instanceof operator can also be used to check if a variable is an instance of the Array constructor. However, this approach might be less reliable if you’re working with arrays that come from different global contexts or iframes.

const myVariable = [1, 2, 3];

if (myVariable instanceof Array) {
console.log('myVariable is an array');
} else {
console.log('myVariable is not an array');
}

Checking whether a variable is an array is a fundamental step in writing robust JavaScript code. By using methods like Array.isArray(), the instanceof operator, you can ensure that your code behaves as expected, preventing errors and ensuring the proper handling of data. Whether you’re building complex web applications , understanding these techniques will contribute to the reliability and stability of your codebase.