Execution of JavaScript

Credit: J. Trauger (JPL/NASA)

There are 5 ways of including JavaScript code in your HTML files:

• You can embed it between <SCRIPT> and </SCRIPT> tags. See this for an example. This is the usual method.
• A second common method is to include JavaScript code as an event handler inside HTML elements in Forms. Typically, the JavaScript code is very small and is usually a call to a function which may carry out complex tasks. See this for the output of a simple example.
• A third, less usual, method, is to use <SCRIPT SRC=...> tags to read in JavaScript source from a file. This is one way to (partially) get around the limitation that Client-Side JavaScript cannot read data from the server -- you can embed data as a JavaScript program. However, the data is in an extremely limited format and would usually be limited to a few hundred values. See this for an example near the end of this file.
• There exist two other methods that are sometimes used: (a) using a special Javascript: URL protocol, and (b) embedding code with the JavaScript HTML entity, but we will not discuss them here.

Class Topics

Client-Side JavaScript

JavaScript as a Programming Language

Execution of JavaScript

"JavaScript" Document Object Model

Programming with JavaScript

Using Cookies in JavaScript

Using JavaScript to Write HTML

JavaScript and DHTML

JavaScript and CGI

Homework Assignments

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