Useful Code Snippets / Tutorials - JavaScript

The JavaScript Source (formerly JavaScripts.com)
The JavaScript Source is a repository of free “cut and paste” JavaScript code, nicely organized by category. Some tutorials are available as well.
Create a multi-state image toolbar on your Web site with this JavaScript guide
This document guides you through the process of using JavaScript and the DOM to build a three-state toolbar that accurately and efficiently handles different button states (normal, highlighted, selected), and the interdependencies between them.
The Perfect Pop-up by Ian Lloyd
This tutorial shows how, with the right thought, pop-up windows can be used without upsetting anyone – particularly the person browsing your site.
Custom Javascript Alert Box
Create your own alert boxes, customized to match your site. Use this script to override the default window.alert method of a browser.
Animated Hovering Windows Using JavaScript
You’ve probably seen many Web sites with windows that seem to appear out of nowhere on the screen. This tutorial will explain how to use that technique to accomplish your own effects.
How to Grey Out the Screen
Ever notice websites that “gray” out a screen in order to show you some important notice (or, sadly, some annoying advertisement)? Well, Patrick Hunlock details how to achieve that effect using a snippet of javascript.
Top 10 JavaScript Snippets for Common Tasks
Web developers often use JavaScript for common tasks on their websites. In this tutorial Scott Clark shows you the top 10 JavaScript snippets you can use on your Web pages by just cutting and pasting!
dTree
dTree is a free JavaScript tree menu. That is very simple to set up and use. You don’t have to worry about adding pages to the tree in a specific order, which makes it ideal for generating a tree from a database.
FreeStyle Menu
A very flexible unlimited-level, drop down JavaScript menu that uses UL/LI list data formatted with a CSS menu layout. It’s powerful, lightweight and extremely easy to use! Note that it is "donation-ware," meaning that if you make a donation to support this script, it may be used on a website without a crediting link.
overLIB
A great little tool for creating nice popup descriptions when someone hovers over some text, an image, etc.
clueTip
A jQuery plugin which allows you to easily show a fancy tooltip when the user’s mouse hovers over (or, optionally, clicks on) any element you designate in your script. If the element includes a title attribute, its text becomes the heading of the clueTip. Recently I have come to prefer this to overLIB.