when an javascript error is occured , instead of showing the default error message by the system, we can show the our own cusom error message like this.

Restrict input to alphanumeric and uppercase

Find and replace a string or character(s) inside another string

check if your browser/javascript supports Ajax.
For this we can use prototype's getTransport method.

I found this to be a neat little trick for hiding(somewhat) source javacscript code from peering eyes...

This function will unload all linked javascript files so that when you view source - you see no javascript files! (Especially helpful when using FF and using web-developer tools - no linked js files are displayed) The files remain resident in memory - allowing for the functions to work.

Just call the function in the tag

Here's a simple JavaScript solution to hide your e-mail from many spam scripts while still providing clickable hyperlinks to your visitors.

Web crawlers and visitors with JavaScript disabled will see: me [at] mydomain [dot] com. I've seen a lot of people that just leave it at this, but it seems a bit unprofessional in my opinion. With the following code, we can replace that with a fully functional hyperlink.

This shows how the computed style of each node differs from the computed style of its parent. The root element, which has no parent, is instead compared against the root of a blank HTML document.

* create a new bookmark called "compute styles" in your firefox toolbar. Place the snippet code in the location field of your "compute styles". click the compute styles bookmark, then click an element on the page with the crosshairs.

A simple demo of the google maps API

Given a PHP array (even a deep nested array), returns a string representation of that array as JavaScript array. Useful when using PHP to output JavaScript.

Similar to Perl's CGI::escapeHTML(), though (because we can!) this adds it as a method to all String objects.