How to Get the Longest String in an Array using JavaScript?

Last Updated : 04 Jul, 2024

Given an array, the task is to get the longest string from the array in JavaScript. Here are a few of the most used techniques discussed with the help of JavaScript. In this article, we will use JavaScript methods to find out the longest string in the array. All approaches are described below with examples.

Table of Content

Using the .sort() Method
Using the reduce() Method
Using JavaScript for Loop
Using the Math.max() and Spread Syntax
Using the filter() Method
Using forEach

Approach 1: Using the .sort() Method

In this approach, we will use the sort() method which calls a function on every 2 elements of the array. It takes 'a' and 'b' 2 arguments and compares their length. If the answer is positive then 'b' is greater else 'a' is greater. This method arranges the elements in the decreasing order of their length and we can access the first element by [0].

Example: This example implements the above approach.

JavaScript

// Input array of strings
let arr = [
    "A_Copmuter_Science_Portal",
    "GeeksforGeeks",
    "GFG",
    "geeks",
];

// It compares the length of an element with
// every other element and after sorting
// them in decreasing order it returns the
// first element.
function longestString() {
    return arr.sort(function (a, b) {
        return b.length - a.length;
    })[0];
}

// Display output
console.log(longestString());

Output

A_Copmuter_Science_Portal

Approach 2: Using the reduce() Method

In this approach, we will use the reduce() method which calls a function on every 2 elements of the array. It takes 'a' and 'b' 2 arguments and compares their length. It returns the elements which have a length greater than every element.

Example: This example implements the above approach.

JavaScript

// Input array of strings
let arr = [
    "A_Copmuter_Science_Portal",
    "GeeksforGeeks",
    "GFG",
    "geeks",
];

// It compares the length of a element with
// every other element and return it if its
// greater than every other element.
function longestString() {
    return arr.reduce(function (a, b) {
        return a.length > b.length ? a : b;
    });
}

// Display output
console.log(longestString());

Output

A_Copmuter_Science_Portal

Approach 3: Using JavaScript for Loop

In this approach, we will use JavaScript for loop to traverse through the array and find the longest string comparing each element.

Example: This example implements the above approach.

JavaScript

// Input array of strings
let arr = [
    "A_Copmuter_Science_Portal",
    "GeeksforGeeks",
    "GFG",
    "geeks",
];

// It compares the length of a string with
// every other string and return it if its
// greater than every other string.
function longestString() {
    let longestString = "";
    for (let i = 0; i < arr.length; i++) {
        if (
            typeof arr[i] === "string" &&
            arr[i].length > longestString.length
        ) {
            longestString = arr[i];
        }
    }
    return longestString;
}

// Display output
console.log(longestString());

Output

A_Copmuter_Science_Portal

Approach 4: Using the Math.max() and Spread Syntax

In this approach, we use the Math.max() function along with the spread syntax (...) to find the length of the longest string in the array. Then, we use the find() method to retrieve the longest string from the array based on its length.

Example:

JavaScript

// Input array of strings
let arr = [
    "A_Copmuter_Science_Portal",
    "GeeksforGeeks",
    "GFG",
    "geeks",
];

// Function to get the longest string in the array
function longestString() {
    // Find the length of the longest string in the array
    let maxLength = Math.max(...arr.map(str => str.length));
    
    // Find the first string in the array with the maximum length
    return arr.find(str => str.length === maxLength);
}

// Display output
console.log(longestString());

Output

A_Copmuter_Science_Portal

Approach 5: Using the filter() Method

In this approach, we will first find the length of the longest string in the array using the map() method and the Math.max() function. Then, we use the filter() method to create a new array containing only the strings with this maximum length. Finally, we return the first element from this filtered array.

Example: In this example, we utilize the filter() method to create a subset of the array containing only the strings that have the maximum length, and then simply return the first element from this subset. This method ensures that even if there are multiple strings with the maximum length, we can handle them efficiently.

JavaScript

// Input array of strings
let arr = [
    "A_Copmuter_Science_Portal",
    "GeeksforGeeks",
    "GFG",
    "geeks",
];

// Function to get the longest string in the array
function longestString() {
    // Find the length of the longest string in the array
    let maxLength = Math.max(...arr.map(str => str.length));
    
    // Filter the array to get all strings with the maximum length
    let longestStrings = arr.filter(str => str.length === maxLength);
    
    // Return the first string with the maximum length
    return longestStrings[0];
}

// Display output
console.log(longestString());

Output

A_Copmuter_Science_Portal

Using forEach

Using forEach to find the longest string in an array involves initializing a variable to store the longest string, then iterating through the array. For each string, compare its length to the current longest string, updating the variable if a longer string is found.

Example: In this example we are following above explained approach.