When let is used to declare the i variable in a loop, the i variable will only be visible within the loop. ... If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail: sales@w3schools.com · If you want to report an error, or if you want to make a suggestion, send us an e-mail: help@w3schools.com · HTML Tutorial CSS Tutorial JavaScript Tutorial How To Tutorial SQL Tutorial Python Tutorial W3.CSS Tutorial Bootstrap Tutorial PHP Tutorial Java Tutorial C++ Tutorial jQuery Tutorial

The JavaScript for of statement loops through the values of an iterable object.

Do not forget to increase the variable used in the condition, otherwise the loop will never end! ... If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail: sales@w3schools.com · If you want to report an error, or if you want to make a suggestion, send us an e-mail: help@w3schools.com · HTML Tutorial CSS Tutorial JavaScript ...

The for...in loop is primarily used for objects to access their property names (keys). for (key in object) { // code block to be executed } key A variable that holds the name (key) of each property during the iterations · object The object ...

A nested loop (a loop inside a loop): let text = ""; for (let = 0; i < 3; i++) { text += i + "<br>"; for (let j = 10; j < 15; j++) { text += j + "<br>"; } } Try it Yourself » · for is an ECMAScript1 (JavaScript 1997) feature. It is supported in all browsers: ❮ Previous JavaScript Statements Next ❯ · ★ +1 · Sign in to track progress · REMOVE ADS · PLUS · SPACES · GET CERTIFIED · FOR TEACHERS · BOOTCAMPS · CONTACT US · × · If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail: sales@w3schools.com ·

The for...in statements combo iterates (loops) over the properties of an object.

The W3Schools online code editor allows you to edit code and view the result in your browser

JavaScript For In Loop. Syntax. For In Over Arrays. Array.forEach(). Lessons for beginners. W3Schools in English

The for...of statements combo iterates (loops) over the values of any iterable.

Learn how to use JavaScript loops effectively with this comprehensive tutorial. Explore about for, while, do...while, for...in, and for...of loops to enhance your coding skills.

In the following example, the code in the loop will run, over and over again, as long as a variable (i) is less than 10: while (i < 10) { text += "The number is " + i; i++; } Try it Yourself » · If you forget to increase the variable used in the condition, the loop will never end.

This is not always the case, JavaScript doesn't care, and statement 3 is optional. Statement 3 can do anything like negative increment (i--), positive increment (i = i + 15), or anything else. Statement 3 can also be omitted (like when you increment your values inside the loop): let i = 0; let len = cars.length; let text = ""; for (; i < len; ) { text += cars[i] + "<br>"; i++; } Try it Yourself »

I completed all the JS exercises on w3schools.com

I have completed the JavaScript For In Loops Exercise at W3Schools.com

December 16, 2025 - Most of the time when you use a loop, you will have a collection of items and want to do something with every item. One type of collection is the Array, which we met in the Arrays chapter of this course. But there are other collections in JavaScript as well, including Set and Map. The basic tool for looping through a collection is the for...of loop:

This chapter of the JavaScript Guide introduces the different iteration statements available to JavaScript. You can think of a loop as a computerized version of the game where you tell someone to take X steps in one direction, then Y steps in another. For example, the idea "Go five steps to the east" could be expressed this way as a loop:

The W3Schools online code editor allows you to edit code and view the result in your browser

January 22, 2016 - Javascript for in loop example program code with output : The for in loop is used to iterate the properties of an object.

In JavaScript, the for loop is used for iterating over a block of code a certain number of times or over the elements of an array. In this tutorial, you will learn about the JavaScript for loop with the help of examples.

Learn how to use for loops in JavaScript to execute code repeatedly, with examples and practical applications.