Checkbox in Java Script

[amar]

Hello Friends

I have make one project in PHP in that i have many of the checkboxes its names are in array e.g. chk[$i]; so $i is variable which will increased in while loop. Now the thing is that I want to put one another checkbox.

Now any of the user click on this checkbox then it will checked automatically all the checkbox. So how it happen ? (Example of yahoo mail , rediffmail etc,. when you want to delete all messages then you have to select single checkbox it will automatically checked all checkbox. Same thing i want )
please if any one knows then send me that javascript.


Thankyou very much ...

[mnuttall]

To see what those sites are doing, right-click and select view source. You might need to past the .js filename into the address bar.