Check if an element is present in an array using JavaScript

JavaScript is a scripting programming language used for both front-end and back-end in web development and it provides a variety of built-in methods to manipulate arrays. In this article, we will see the different methods for checking whether the element is present in the given array or not.

Checking an element that exists in an array is a simple programming task and there are different ways to achieve this in JavaScript. We can find element arrays using both built-in functions and non-built-in functions. There are different approaches to finding an element present in an array, which is described below:

Approach 1: Using includes() method

This method can be utilized to find whether a particular element is present in the array or not. it returns true or false i.e., If the element is present, then it returns true otherwise false. 

Example: In this example, the array is declared and by using the includes() method, & we can check the value present in the array.

Javascript

// Define an array
const arr = [21, 12, 13, 45, 54];

// Check if the array includes the value 12
if (arr.includes(12)) {
    console.log("12 is present in the array.");
} else {
    console.log("12 is not present in the array.");
}

Output:

12 is present in the array

Approach 2: Using the indexOf() method

This method can be used to find used the index of the first occurrence of the search element provided as the argument to the method. 

Example: In this example, an array is declared and by using indextOf() function, we can check the value present in the array.

Javascript

// Define an array
const arr = [10, 72, 3, 14, 5];

// Check if the array includes the value 3
if (arr.indexOf(3) >= 0) {
    console.log("3 is present in the array.");
} else {
    console.log("3 is not present in the array.");
}

Output:

3 is present in the array

Approach 3: Using the find() method

This method is used to get the value of the first element in the array that satisfies the provided condition. It checks all the elements of the array and whichever the first element satisfies the condition is going to print.

Example: In this example, an array is declared, and by using the find() function, we can check the value present in the array.

Javascript

// Define an array
const arr = [5, 20, 30, 40, 50];

// Use the find() method to check if the
// value 30 is present in the array
const result = arr.find(element => element === 30);

// Check the result and log a message
if (result !== undefined) {
    console.log("30 is present in the array.");
} else {
    console.log("30 is not present in the array.");
}

Output:

30 is present in the array

Approach 4: Using the for() Loop

The for loop facilitates the execution of a set of instructions repeatedly until some condition evaluates and becomes false.

Example: In this example, an array is declared by using for() loop iteration up to the element found. By using this, we can check the value present in the array or not.

Javascript

// Define an array
const array1 = [13, 23, 33, 43, 53];

// Initialize a flag variable
let p = false;

// Iterate through the array and check each element
for (let i = 0; i < array1.length; i++) {
    if (array1[i] === 53) {
        p = true;
        break;
    }
}

// Check the flag variable and log a message
if (p) {
    console.log("53 is present in the array.");
} else {
    console.log("53 is not present in the array.");
}

Output:

53 is present in the array

Approach 4: Using the Array.some() method

Algorithm: 

• Initialize the array. 
• Use some method on for loop with some condition which matches the required element and returns true if matches. 
• Print the evaluated result.  

Example:  By using some(), we can check the value present in the array or not.

Javascript

// Define an array
const arr = [5, 20, 30, 40, 50];

// Use the some() method to check if the
// value 30 is present in the array
const result = arr.some(element => element === 30);

// Check the result and log a message
if (result !== undefined) {
    console.log("30 is present in the array.");
} else {
    console.log("30 is not present in the array.");
}

Output:

30 is present in the array.

Time complexity: O(N), Where N is the length of the Array. 

Auxiliary complexity: O(1), Because no extra space is used.