Visit the Understanding the DOM - Document Object Model Series if you want to learn more about this topic. An understanding of DOM Manipulation in JavaScript.This article gives a thorough explanation of how forEach loops work.

To learn more about loops, visit this article called For Loops, For…Of Loops and For…In Loops in JavaScript.

An understanding of JavaScript for and forEach loops.

The How To Build a Website With CSS series can help you to achieve this. You can simply use the addEventListener() method to register an event handler to listen for the browser window resize event, such as window.addEventListener(. The How To Build a Website with HTML series is a great place to start. To successfully complete this tutorial, you will need the following: You will also implement React Observer in your own front end code and test for browser support. In this tutorial, you will learn about basic usage of React Observer. This is more and more frequent with modern single-page apps. There’s also another use case for the Resize Observer API that the window’s resize event can’t help us with: when elements are added or removed from the DOM dynamically, influencing the size of the parent element. In other words, using window.resize is often wasteful because it informs us of every viewport size change, not just when an element’s size actually changes. This can easily lead to performance problems due to the large amount of triggered event. Up until this point, we’ve had to rely on the global window.resize event to listen for resize events and check if certain elements have changed size. The most frequent reason for an element’s size to change is when the viewport is resized or the device’s direction changes between portrait and landscape. It allows for elements to be notified when their size changes. Here's a common debounce floating around the net, though do look for more advanced ones as featuerd in lodash.Resize Observer is a new JavaScript API that’s very similar to other observer APIs like the Intersection Observer API. Window.addEventListener('resize',debounce(handler, delay, immediate),false) Use a debounce function to mitigate the excess calls. The resize event should never be used directly as it is fired continuously as we resize.

Javascript window resize