Including JavaScript Codes as External Files

JavaScript Tutorials - Herong's Tutorial Examples

Dr. Herong Yang, Version 2.11

<< JavaScript Tutorials - Herong's Tutorial Examples

This section provides a quick description of how to save JavaScript codes into separate files and include them into HTML documents with 'script' tags. A tutorial example is provided on calling a function stored in a separate JavaScript file.

Sometime, if you have a large amount of JavaScript code that needs to be shared by multiple HTML documents, you can store the JavaScript code in a separate file, and use the "script" tag to retrieve this tile.

The syntax of the "script" tag to retrieve a separate JavaScript code looks like this:

<script type="text/javascript" src="JavaScript_file_URL">
</script>

To test this feature, I wrote this JavaScript code and saved as a file, Hello_World_Function.js:

function printHello() {
   document.write('Hello World!');
}

Now I can modify my HTML document in the previous section to retrieve this file with a "script" tag:

<html>
<!-- Hello_World_Include.html
   Copyright (c) 2008 by Dr. Herong Yang, http://www.herongyang.com/
-->
<head>
<title>printHello() Function in an Include File</title>
<script type="text/javascript" src="Hello_World_Function.js">
</script>
</head>
<body>
<pre>
<script type="text/javascript">
   printHello();
</script>
</pre>
</body>
</html>

Of course, the output of the modified JavaScript page will be the same text: "Hello World!".

While testing this "src" attribute of the "script" tag, I also notice that the shorthand form of the empty tag does not work:

<script type="text/javascript" src="JavaScript_file_URL"/>

You must use the close tag </script> explicitly!

Sections in This Chapter

JavaScript Support in Web Browsers

Including JavaScript Codes with HTML "script" Tags

Including 'script' Tags in String Literials

Escaping 'script' Tags in String Literials

Using HTML Entities to Protect HTML Tags

Including JavaScript Codes as External Files

DOM API - The "document" Object

DOM API - The "window" Object

Event Listeners and Objects

'javascript:' Pseudo-URL Addresses

Dr. Herong Yang, updated in 2008

Including JavaScript Codes as External Files