How to find the longest word within the string in JavaScript ?

To find the longest word within the string in JavaScript we will compare the counts to determine which word has the most characters and return the length of the longest word.

Example:

Input: "This is a demo String find the largest word from it"
Output: "largest"

Input:  "Hello guys this is geeksforgeeks where students learn programming"
Output: "geeksforgeeks"

We can use the following approaches to find the longest word within the string in JavaScript:

Using regex and for…loop

Here, we use regex to split the string into an array of words by using the regex /[a-zA-Z0-9]+/gi and then using for loop iterate the array and search the largest string.

Example: This example uses the above-explained approach.

Javascript

// Javascript program to search largest word from a string

function longest(str) {

    // Split the string using regex
    str = str.match(/[a-zA-Z0-9]+/gi);
    // Creating a empty string to store largest word
    let largest = "";

    // Creating a for...loop to iterate over the array
    for (let i = 0; i < str.length; i++) {

        // If the i'th item is greater than largest string
        // then overwrite the largest string with the i'th value
        if (str[i].length > largest.length) {
            largest = str[i];
        }
    }
    return largest;
}

console.log(
    longest(
        "Hello guys this is geeksforgeeks where" +
            " students learn programming"
    )
);

Output

geeksforgeeks

By using the split() and sort() method

Here, we split the string using the String.split() method and sort the array using the Array.sort() method. 

Example: This example uses the above-explained approach.

Javascript

function longest(str){
    // Split the string into array
    str = str.split(" ")
    // Return the first sorted item of the Array
    return str.sort((a, b) => b.length - a.length)[0]
}

console.log(longest("Hello guys this is geeksforgeeks"+
                        " where students learn programming"))

Output

geeksforgeeks

Approach 3: Using split() and reduce() methods

Here, we will split the string using the String.split() method, and by using the reduce method we search for the largest element of the array, which is your largest string.

Example: This example uses the above-explained approach.

Javascript

function longest(str) {
    // Split the string into array
    str = str.split(" ");

    // Get the index of largest item of the array
    let index = str.reduce((acc, curr, i) => {
        if (curr.length > str[acc].length) {
            return i;
        }
        return acc;
    }, 0);

    return str[index];
}

console.log(
    longest(
        "Hello guys this is geeksforgeeks" +
            " where students learn programming"
    )
);

Output

geeksforgeeks

Using split() and for…loop

Here, we will split the string and before that, we will declare an empty string in order to store the resulted from the longest string in it. Also, we will be using an arrow function and this whole task will be performed under it only.

Example: This example uses the above-explained approach.

Javascript

// JavaScript code to for the above approach..

let longestWord = (string) => {
    let stringg = string.split(" ");
    let longest = 0;
    let longest_word = null;
    for (let i = 0; i < stringg.length; i++) {
        if (longest < stringg[i].length) {
            longest = stringg[i].length;
            longest_word = stringg[i];
        }
    }
    return longest_word;
};

console.log(
    longestWord(
        "Hello guys this is geeksforgeeks where students learn programming"
    )
);

Output

geeksforgeeks

Using sort() method

To find the longest word within a string in JavaScript using the sort method, you can follow these steps:

1. Split the string into an array of words.
2. Use the sort method to sort the array based on the length of each word.
3. Retrieve the last (or first, depending on the sorting order) element of the sorted array, as it will be the longest word.

Example: Here, the findLongestWord function takes an input string, splits it into an array of words, sorts the array based on the length of each word in descending order, and then returns the longest word.

Javascript

function findLongestWord(inputString) {
    // Step 1: Split the string into an array of words
    const wordsArray = inputString.split(/\s+/);

    // Step 2: Sort the array based on word length
    const sortedWords = wordsArray.sort(function (a, b) {
        return b.length - a.length; // Sort in descending order by word length
    });

    // Step 3: Retrieve the longest word (first element after sorting)
    const longestWord = sortedWords[0];

    return longestWord;
}

// Example usage:
const inputString = "JavaScript is an awesome programming language";
const result = findLongestWord(inputString);

console.log("Longest word:", result);

Output

Longest word: programming