Check if a value exists in array in Javascript

In this chapter, you will learn about how to check if a value exists in an array in Javascript. When you have an array of the elements, and you need to check whether the certain value exists or not.

Solution 1:
includes(): We can use an includes(), which is an array method and return a boolean value either true or false. If the value exists returns true otherwise it returns false. Let’s write an example of the same.

var persons = ["John", "Mickel", "Stark"];
var searchResult = persons.includes("John");

console.log(searchResult);

// Output
// true

The content of the array can be anything like string or numbers.

var gameScore = [100,10,89,60,50];
var searchResult = gameScore.includes(60);

console.log(searchResult);

// Output
// true

Solution 2:
indexOf(): You can also use the method indexOf(), which returns the first index at which a given element can be found in the array, otherwise -1. let’s write an example for the same

var gameScore = [100,10,89,60,50];
var searchResult = gameScore.indexOf(60);

console.log(searchResult);

// Output
// 3

//Try with number which doesnot exists

var gameScore = [100,10,89,60,50];
var searchResult = gameScore.indexOf(67);

console.log(searchResult);

// Output
// -1

Solution 3:
We can also use the for loop, with the matching condition, let’s write an example for the same

var gameScore = [100,10,89,60,50];

var depth = gameScore.length;
while (depth--) {
  if (gameScore[depth] === 100) {
      console.log('The value exist...');
  }
}
    
// Output
// The value exist...