How to Check if Array Includes Element in JavaScript

Use the includes() method on an array to check if it contains a specific element. It returns true if the element is found, otherwise false. For example, array.includes(element).

Syntax

The includes() method is called on an array and takes one required argument: the element to search for. It returns a boolean indicating if the element exists in the array.

• array: The array you want to check.
• element: The value you want to find in the array.

javascript

array.includes(element)

Example

This example shows how to check if the number 3 is in the array. It prints true if found, otherwise false.

javascript

const numbers = [1, 2, 3, 4, 5];
const hasThree = numbers.includes(3);
console.log(hasThree);

Output

true

Common Pitfalls

One common mistake is using includes() with objects or arrays inside arrays, which checks by reference, not by value. Also, includes() is case-sensitive for strings.

Wrong example: searching for an object inside an array of objects will fail unless it is the exact same object.

javascript

const arr = [{id: 1}, {id: 2}];
console.log(arr.includes({id: 1})); // false because different object reference

// Correct way: check by property
const found = arr.some(item => item.id === 1);
console.log(found); // true

Output

false
true

Quick Reference

Method	Description	Returns
includes(element)	Checks if element exists in array	true or false
some(callback)	Checks if any element passes test	true or false
indexOf(element)	Returns index or -1 if not found	number

Key Takeaways

Use includes() to check if an array contains a specific element easily.

includes() returns true or false based on presence of the element.

For objects or complex types, use some() with a test function instead.

includes() is case-sensitive for strings and checks by strict equality.

Remember includes() works on arrays and strings in JavaScript.