How do I check if an array includes a value in JavaScript?

In this article, you'll learn to check if an array includes a value in JavaScript.
Submitted by Pratishtha Saxena, on May 09, 2022

To check if an array includes a value, we can use two methods:

  1. includes()
  2. indexoOf()

Here the value can be anything, it can be a string or any number. Using the following method, you can check any string or number in the given array.

1) Using includes() Method

There is a method in JavaScript to do this task very easily. Using includes() method we can check whether a particular value is present in the given array or not. This value to be checked is given inside the brackets.

Syntax:

array.includes('value');

It gives the result true/false. Also, keep in mind that includes() is case sensitive. So basically, this is a very simple way of doing this.

Example 1:

const names = ['John', 'Peter', 'James', 'Jason', 'William'];
let result = names.includes('Peter');
console.log(result);

Output:

true

Example 2:

const names = ['John', 'Peter', 'James', 'Jason', 'William'];
let result = names.includes('Vicky');
console.log(result);

Output:

false

1) Using indexoOf() Method

There is another method called indexoOf(), but this is not the direct method to find a value in an array. Here the value is given with a condition for its index. If the condition is true, it will return true, else false.

Syntax:

array.indexOf('value') !== -1;

It explains that if the index of the given value is not equal to -1 then obviously that the given value is in the given array and hence this will return true, else false.

Example 3:

const names = ['John', 'Peter', 'James', 'Jason', 'William'];
let result = names.indexOf('James') !== -1;
console.log(result);

Output:

true

Example 4:

const names = ['John', 'Peter', 'James', 'Jason', 'William'];
let result = names.indexOf(5) !== -1;
console.log(result);

Output:

false

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