Using the <script> Element to Link External Files
Completion requirements
The second way is to place JavaScript code in an external file and import it into the document. The second method is preferred because, with large programs, it is hard to maintain everything in an HTML document. JavaScript files have the file extension ".js". An example is:
<script src="myprogram.js"></script>
Although all JavaScript code should be in a .js file because our programs are short, we'll place code directly within a <script> tag. We'll use external .js files in the next course.
Examples
Basic usage
These examples show how to import (an external) script using the <script> element.
<script src="javascript.js"></script>
And the following examples show how to put (an inline) script inside the <script> element.
<script>
alert("Hello World!");
</script>