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Introduction JS: DOM API

Today’s websites are highly interactive. Pages rarely reload, so we can change their content instantly.

Software solutions have become so complex. Now we can open a browser and use programs like Photoshop, packages similar to Microsoft Office, or full-blown development environments such as our Hexlet editor.

Browser games are an enormous industry too. These games are no worse than regular desktop ones, thanks to hardware support.

None of this would be possible without JavaScript.

JavaScript, which was originally used to add snowflakes to a web page, has become a powerful tool for professionals. To date, JavaScript is the only language that browsers can execute.

But a language is not enough to bring a page to life. The browser should provide a way to manage both the pages and the browser itself. Most of these features are standardized and described in the HTML5 specifications. Some of them are:

  • Manipulating page content
  • Managing appearance
  • Responding to user actions
  • Working with cookies
  • Controlling the browser's address bar, navigation, history
  • Interacting with the server
  • Video playback
  • Input/Output
  • Interacting with file systems and networks
  • 2D/3D drawing

From the language’s point of view, most of these features look like global objects that you can interact with within the program. The most basic and important object in this system is the DOM tree.

In this course, we’ll learn how to implement JavaScript on a website, go through the fundamental ways to modify a page, get acquainted with polyfills, make our first Ajax request, and discover the world of events.

After this course, you’ll try your hand at creating simple front-end games.

How to prepare for the course

This course is about animating pages in browsers using JavaScript. This course assumes that you’ve already studied JavaScript, either in Hexlet or on any other platform.

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