Most programs use variables. This lesson explains what variables are.

Here are some common errors people make in JavaScript.

The JavaScript property length returns the number of elements in an array. Right? Er, well, ...

Create a quiz about yourself.

You’ll learn how to use focus() to improve a page’s usability.

Learn some more JavaScript/jQuery:

• Learn how to set the text of an element, with text("stuff").
• Learn how to get the text of an element, with text().
• Learn how to add a CSS class to an element, with addClass().
• Learn how to remove a CSS class from an element, with removeClass().

Good reference for HTML, CSS, and JavaScript.

In this lesson, you will learn that:

• Some programs run inside browsers.
• Those programs are downloaded along with pages.
• Every major browser can run JavaScript programs.
• Programs are triggered by events.
• JavaScript is used for interface effects, validating form data, input widgets, and sending data to a server.

Learn:

• Syntax bugs happen when you type something the browser doesn’t understand, like alrt().

• Use Firefox’s error console to track down syntax errors.

• Logic errors are when you tell the browser to do the wrong thing.

• Use alert() statements to track program execution. If alert messages are supposed to show up, but don’t, you know what code is not executing.

• Use alert() statements to look at the values of variables.

Learn:

• How to report errors in a professional way.

• How page-wide, global error messages help the user.

• How JavaScript functions make error reporting easier to program.