JavaScript and HTML

Within a browser, JavaScript doesn't do anything by itself. You run JavaScript from inside your HTML webpages. To call JavaScript code from within HTML, you need the <script> element. There are two ways to use script, depending on whether you're linking to an external script or embedding a script right in your webpage.

Usually, you'll be writing scripts in their own .js files. If you want to execute a .js script from your webpage, just use <script> with an src attribute pointing to the script file, using its URL:

<script src="path/to/my/script.js"></script>

You may also add JavaScript code between <script> tags rather than providing an src attribute.

<script>
window.addEventListener('load', function () {
  console.log('This function is executed once the page is fully loaded');
});
</script>

That's convenient when you just need a small bit of JavaScript, but if you keep JavaScript in separate files you'll find it easier to

• focus on your work
• write self-sufficient HTML
• write structured JavaScript applications