Skip to content

JavaScript for loop

  • by

The for loop is a control flow statement in JavaScript that allows you to execute a block of code repeatedly. The loop has three optional expressions, enclosed in parentheses, which are separated by semicolons.

for (initialization; condition; increment/decrement) {
  // code to be executed
  • Initialization: This expression is executed only once before the loop starts. It is typically used to initialize a counter variable.
  • Condition: This expression is evaluated at the beginning of each loop iteration. If the condition is true, the loop continues; if it is false, the loop ends.
  • Increment/decrement: This expression is executed at the end of each loop iteration. It is typically used to update the counter variable.

JavaScript for loop example

Simple example code loop from 0 to 4.

<!DOCTYPE html>
    for (let i = 0; i < 5; i++) {
        console.log("i value = ", i);



JavaScript for loop

Loop through an array

const arr = [1, 2, 3];
for (let i = 0; i < arr.length; i++) {

Loop through an object’s properties

const obj = {a: 1, b: 2, c: 3};
for (let prop in obj) {
  console.log(`${prop}: ${obj[prop]}`);

JavaScript Infinite for loop

If the test condition in a for loop is always true, it runs forever (until memory is full). For example,

// infinite for loop
for(let i = 1; i > 0; i++) {
    // block of code

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

Leave a Reply

Your email address will not be published. Required fields are marked *