Running JavaScript in the browser

Every browser ships with a built-in JavaScript engine, so there's nothing to install to start running JavaScript — you just need a way to get your code onto a page. The most common way is the <script> tag, placed inside an HTML file.

<script>
  console.log('Hello from inline JavaScript!');
</script>

Writing JavaScript directly inside a <script> tag works fine for tiny experiments, but most real projects keep their JavaScript in a separate file (often named something like script.js) and link it into the HTML instead. This keeps HTML and JavaScript organized and lets the same script be reused across multiple pages.

<script src="script.js"></script>

To link an external JavaScript file to an HTML page, you use a <script> tag with a ____ attribute pointing to the file.

Why do many developers prefer linking an external .js file instead of writing JavaScript directly inside a <script> tag?

Every modern web browser has a built-in JavaScript engine, so users don't need to install anything extra to run JavaScript on a webpage.

You'll often see <script> tags placed near the end of the <body>, right before it closes. That way the browser finishes loading the page's visible content first, before it starts downloading and running the JavaScript.