How to check if an Array includes a value in JavaScript

In this tutorial you will learn 5 ways to check if a JavaScript array includes a value.

1. Array.forEach() method

We can iterate through an array to check if the value is present in the array.

forEach() method takes a callback function, which gets executed once for every element in the array.

const countries = ["India", "England", "USA", "Spain"]

let isFound = false;
countries.forEach((country)=>{
  if (country === 'Spain') {
    isFound = true;
    return;
  }
  isFound = false;
})

console.log(isFound) // true

2. Array.includes() method

includes method returns true if a value is present in an array else it returns false.

const countries = ["India", "England", "USA", "Spain"]

countries.includes("France") 
 // false

countries.includes("England") 
// true

3. Array.indexOf() method

indexOf method returns the first index of the matched element, it returns -1 if the value is not present in the array.

```javascript
const countries = ["India", "England", "USA", "Spain"]

countries.indexOf("France") 
 // -1

countries.indexOf("England") 
// 1

Check for an Object in an Array

Let's consider we have an array of objects

const users = [{id: 1, name: 'suraj'}, {id: 2, name: 'Mark'}]

4. Array.some() method

If you have an array of objects and want to know whether an object is present in the array or not then you can consider using Array.some()

some() method takes a callback function, which gets executed once for every element in the array until it finds an element where the callback returns true.

some() returns true if the object is present in the array else it returns false

const objectToFind = {id:2, name: 'Mark'}

const isObjectFound = users.some((user)=> {
  return user.id === objectToFind.id && user.name === objectToFind.name
})

console.log(isObjectFound) // true

5. Array.find() method

It behaves similar to the some() method but instead of returning a boolean value, it returns the matched value from the array or it returns undefined if the value is not present in the array.

const objectToFind = {id:2, name: 'Mark'}

const foundObject = users.find((user)=> {
  return user.id === objectToFind.id && user.name === objectToFind.name
})

console.log(isObjectFound) // {id:2, name: 'Mark'}

const notfoundObject = users.find((user)=> {
  return user.id === 3 && user.name === 'Nick'
})

console.log(notfoundObject) // undefined

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