Javascript Tutorial

Javascript - Intro
Javascript - Syntax
Javascript - Location
Javascript - External
Javascript - Operators
Javascript - Variables
Javascript - Functions
Javascript - Events
Javascript - Statements
Javascript - If
Javascript - Else If
Javascript - While
Javascript - For Loop
Javascript - Comments
Javascript - Array
Javascript - Alert
Javascript - Confirm
Javascript - Prompt
Javascript - Print
Javascript - Redirect
Javascript - Pop Up
Javascript - Date
Javascript - Form
Javascript - Void 0

Javascript String

Javascript - Strings
Javascript - Length
Javascript - Split
Javascript - Search
Javascript - Replace
Javascript - indexOf
Javascript - Compare

Javascript Advanced

Javascript - getElementById
Javascript - innerHTML

External Javascript Files

Having already dicussed placing Javascript in the head and body of your HTML document, let us now explore the third possible location, an external file. If you have ever used external CSS this lesson will be a cinch.

Importing an External Javascript File

Importing an external file is relatively painless. First the file you are importing must be valid Javascript, and only Javascript. Second, the file must have the extension ".js". Lastly, you must know the location of the file.

Let us assume we have a file "myjs.js" that contains a one line Hello World alert function. Also, let us assume that the file is the same directory as our HTML file we are going to code up. To import the file you would do the following in your HTML document.

HTML & JavaScript Code:

<html>
<head>
<script src="myjs.js">
</script>
</head>
<body>
<input type="button" onclick="popup()" value="Click Me!">
</body>
</html>

Display:

Great Javascript Repositories

There is a ton of great stuff you can do with Javascript, if you know how to code like Paul Allen and Bill Gates, but for the rest of us it is nice to get incredible Javascript tools without having to write them ourselves. Below are some of the better Javascript resources on the web these days.

External File Tips & Recap

Use external Javascript files when you want to use the same script on many pages, but don't want to have to rewrite the code on every page!
Use external Javascript files for including both types of scripts! The type that you place in the head (functions) and the type you place in the body (scripts you want to run when the page loads).
Be sure that your Javascript files (.js) do not include the <script> tag. They should only have the HTML comment and Javascript code.