Reverse a String in JavaScript

In this article, we are given an input string and the task is to reverse the input string. We have various methods to reverse a string in JavaScript, some of them are described below with examples.

Examples:

Input: str = "Geeks for Geeks"
Output:  "skeeG rof skeeG"

Input: str = "Hello"
Output: "olleH"

Method 1:

• Check the input string if a given string is empty or just has one character or it is not of string type then it returns “Not Valid string”.
• If the above condition is false create an array where we can store the result. Here revArray[] is the new array.
• Loop through the array from the end to the beginning and push each and every item in the array revArray[].
• Use the join() prebuilt function in JavaScript to join the elements of an array into a string.

Example: This example shows the above-explained approach.

javascript

<script>
    function ReverseString(str) {

        // Check input
        if(!str || str.length < 2 ||
                typeof str!== 'string') {
            return 'Not valid';
        }

        // Take empty array revArray
        const revArray = [];
        const length = str.length - 1;

        // Looping from the end
        for(let i = length; i >= 0; i--) {
            revArray.push(str[i]);
        }

        // Joining the array elements
        return revArray.join('');
    }

    console.log(ReverseString("Geeks for Geeks"))
</script>

Output:

skeeG rof skeeG

Method 2:

• Use split() inbuilt function in JavaScript to split a string into an array of characters i.e. [ ‘G’, ‘e’, ‘e’, ‘k’, ‘s’, ‘ ‘, ‘f’, ‘o’, ‘r’, ‘ ‘, ‘G’, ‘e’, ‘e’, ‘k’, ‘s’ ]
• Use the reverse() function in JavaScript to reverse the array of characters i.e. [ ‘s’, ‘k’, ‘e’, ‘e’, ‘G’, ‘ ‘, ‘r’, ‘o’, ‘f’, ‘ ‘, ‘s’, ‘k’, ‘e’, ‘e’, ‘G’ ]
• Use join() function in JavaScript to join the elements of an array into a string.

Example: This example shows the above-explained approach.

javascript

<script>
    // Function to reverse string
    function ReverseString(str) {
    return str.split('').reverse().join('')
    }

    // Function call
    console.log(ReverseString("Geeks for Geeks"))
</script>

Output:

skeeG rof skeeG

Method 3: 

• Use the spread operator instead of a split() function to convert the string into an array of characters i.e. [ ‘G’, ‘e’, ‘e’, ‘k’, ‘s’, ‘ ‘, ‘f’, ‘o’, ‘r’, ‘ ‘, ‘G’, ‘e’, ‘e’, ‘k’, ‘s’ ]. Learn more about the spread operator here Spread Operator
• Use the reverse() function in JavaScript to reverse the array of characters i.e. [ ‘s’, ‘k’, ‘e’, ‘e’, ‘G’, ‘ ‘, ‘r’, ‘o’, ‘f’, ‘ ‘, ‘s’, ‘k’, ‘e’, ‘e’, ‘G’ ]
• Use the join() function in JavaScript to join the elements of an array into a string.

Example: This example shows the above-explained approach.

javascript

<script>
    const ReverseString = str => [...str].reverse().join('');

    console.log(ReverseString("Geeks for Geeks"))
</script>

Output:

skeeG rof skeeG

Method 4:

• Use the spread operator to convert a string into an array of characters.
• Use reduce() function in JavaScript to make a reverse string from an array by concatenating the string in the forward direction.

Example: This example shows the above-explained approach.

Javascript

<script>
    // Function to reverse the string
    function ReverseString(str) {

            // Returning reverse string
        return [...str].reduce((x, y) => y.concat(x));
    }

    console.log(ReverseString("Geeks for Geeks"))
</script>

Output:

skeeG rof skeeG