Here is a simple JavaScript example which will generate a simple alert box based on clicking a link or a form button. Useful for alerting users for missing fields, displaying a message on document open or close, or informing users they’ve clicked a link, etc.

The author notes, "The JavaScript confirm alert box differs from a regular alert box in that it provides two choices for the user, OK and Cancel. Typically, you’ll see confirmation boxes utilized on links where the destination is outside the domain of the page you’re currently on or to alert you of potentially objectionable material. The following example will display a confirmation alert box when either a link or form button is clicked. Once either OK or Cancel are selected an alert box will follow to display which was chosen."

Use this custom DHTML "widget" to uniquely present new or notable pieces of information to your visitors. The interface is cross browser compatible, and can be dragged/ hidden freely by the user.

Auto-prompt users to bookmark your homepage using this simple IE-only script! This script uses a simple browser detect which activates or avoids an alert box. This is a simple, yet effective use of this IE-only feature.

This JavaScript shows a very simple example of how to create a button that does something JavaScript-like in nature when it is clicked. The alert() function is predefined: we could have made our own function and then called it upon the onClick event.

Forget about browser ugly alert box, create your own alerts with animated button, graphics border and transitions.

This DHTML ad script displays an "inexcusable" box in the middle of the page, broadcasting ads of your choice inside. The box automatically disappears after x seconds, with its display frequency configurable.

Personalize your web page with this very simple paste-it-in script that asks the vistor for his or her name when entering your page, then prints a "Hello" welcome message anywhere you wish in the body of the page. (If the visitor does not type in a message, a default message shows, instead.) Very easy install for JavaScript newcomers.

Tigra Hints is free JavaScript widget that displays pop-up box with notes (also known as tooltips or hints) when mouse appears over any HTML element on the page. Any HTML is welcome inside the box: lists, tables, images etc. This component makes the site more informative and easy to use while saving valuable space.

This script will make a box with your message fly in over the screen, stay where you want it to, then dissapear after a certain amount of time.