JavaScript Program to Find Sum of Even Numbers of an Array
Last Updated :
26 Feb, 2024
In JavaScript, working with arrays is a basic operation. We have to sum all the even numbers present in the array. We can check the number if it is even or not by the use of the % operator.
These are the following ways to find the sum of Even numbers in an Array:
Sum of Even Numbers of an Array using Iterative Approach
This method iterates through each element in the array and checks if it's even. If it is, the element is added to a running total variable, which stores the cumulative sum of all even numbers encountered so far.
Example: The function `sumOfEvenNumbers` calculates the sum of even numbers in an array using a loop and conditional statements.
JavaScript
function sumOfEvenNumbers(arr) {
let sum = 0;
for (let i = 0; i < arr.length; i++) {
if (arr[i] % 2 === 0) {
sum += arr[i];
}
}
return sum;
}
const numbers = [1, 2, 3, 4, 5];
const evenSum = sumOfEvenNumbers(numbers);
console.log("Sum of even numbers:", evenSum);
OutputSum of even numbers: 6
Sum of Even Numbers of an Array using filter() and reduce() methods
This method provides a simpler answer by using built-in array functions. By using the filter method, an array is created that is limited to the even elements present in the original array. The filtered array is then iterated by using the reduce method, which adds each element to the sum.
Example: The `sumOfEvenNumbers` function filters the even numbers from the input array using the `filter` method and then calculates their sum using the `reduce` method.
JavaScript
function sumOfEvenNumbers(arr) {
return arr.filter(num => num % 2 === 0)
.reduce((acc, num) => acc + num, 0);
}
const numbers = [1, 2, 3, 4, 5];
const evenSum = sumOfEvenNumbers(numbers);
console.log("Sum of even numbers:", evenSum);
OutputSum of even numbers: 6
Sum of Even Numbers of an Array using Recursive Approach
This method solves the problem by using recursion. It defines a function that accepts three parameters: the array, the current index, and the sum of the total. After checking that the array has ended in the base case, the function calls itself recursively with the next element and, if the current number is even, changes the total.
Example: Recursive function `sumOfEvenNumbers` computes the sum of even numbers in an array. It recursively processes the array, adding even numbers to the sum. The base case returns 0 if the array is empty.
JavaScript
function sumOfEvenNumbers(arr) {
// Base case: If the array is empty, return 0.
if (arr.length === 0) {
return 0;
}
const firstElement = arr[0];
const restOfArray = arr.slice(1);
if (firstElement % 2 === 0) {
return firstElement +
sumOfEvenNumbers(restOfArray);
} else {
return sumOfEvenNumbers(restOfArray);
}
}
const numbers = [1, 2, 3, 4, 5, 6];
const evenSum = sumOfEvenNumbers(numbers);
console.log("Sum of even numbers:", evenSum);
OutputSum of even numbers: 12
Sum of Even Numbers of an Array using Using forEach Loop
This method uses forEach to iterate through the array, providing an alternative to the normal loop. It keeps readability and efficiency while providing a slightly more simple solution.
Example: The `sumOfEvenNumbers` function calculates the sum of even numbers in an array using a forEach loop. It iterates through the array, adding each even number to the sum. The example demonstrates its usage by finding the sum of even numbers in an array and printing the result.
JavaScript
function sumOfEvenNumbers(arr) {
let sum = 0;
arr.forEach(num => {
// Check if the current element is even.
if (num % 2 === 0) {
// If the current element
// is even, add it to the sum.
sum += num;
}
});
// Return the total sum of even numbers.
return sum;
}
const numbers = [1, 2, 3, 4, 5, 6];
const evenSum = sumOfEvenNumbers(numbers);
console.log("Sum of even numbers:", evenSum);
OutputSum of even numbers: 12
Similar Reads
Non-linear Components In electrical circuits, Non-linear Components are electronic devices that need an external power source to operate actively. Non-Linear Components are those that are changed with respect to the voltage and current. Elements that do not follow ohm's law are called Non-linear Components. Non-linear Co
11 min read
JavaScript Tutorial JavaScript is a programming language used to create dynamic content for websites. It is a lightweight, cross-platform, and single-threaded programming language. It's an interpreted language that executes code line by line, providing more flexibility.JavaScript on Client Side: On the client side, Jav
11 min read
Web Development Web development is the process of creating, building, and maintaining websites and web applications. It involves everything from web design to programming and database management. Web development is generally divided into three core areas: Frontend Development, Backend Development, and Full Stack De
5 min read
Spring Boot Tutorial Spring Boot is a Java framework that makes it easier to create and run Java applications. It simplifies the configuration and setup process, allowing developers to focus more on writing code for their applications. This Spring Boot Tutorial is a comprehensive guide that covers both basic and advance
10 min read
Class Diagram | Unified Modeling Language (UML) A UML class diagram is a visual tool that represents the structure of a system by showing its classes, attributes, methods, and the relationships between them. It helps everyone involved in a projectâlike developers and designersâunderstand how the system is organized and how its components interact
12 min read
React Interview Questions and Answers React is an efficient, flexible, and open-source JavaScript library that allows developers to create simple, fast, and scalable web applications. Jordan Walke, a software engineer who was working for Facebook, created React. Developers with a JavaScript background can easily develop web applications
15+ min read
Steady State Response In this article, we are going to discuss the steady-state response. We will see what is steady state response in Time domain analysis. We will then discuss some of the standard test signals used in finding the response of a response. We also discuss the first-order response for different signals. We
9 min read
JavaScript Interview Questions and Answers JavaScript (JS) is the most popular lightweight, scripting, and interpreted programming language. JavaScript is well-known as a scripting language for web pages, mobile apps, web servers, and many other platforms. Both front-end and back-end developers need to have a strong command of JavaScript, as
15+ min read
React Tutorial React is a JavaScript Library known for front-end development (or user interface). It is popular due to its component-based architecture, Single Page Applications (SPAs), and Virtual DOM for building web applications that are fast, efficient, and scalable.Applications are built using reusable compon
8 min read
Backpropagation in Neural Network Back Propagation is also known as "Backward Propagation of Errors" is a method used to train neural network . Its goal is to reduce the difference between the modelâs predicted output and the actual output by adjusting the weights and biases in the network.It works iteratively to adjust weights and
9 min read