reading value of textbox

If there are square brackets [] in name of an item in a form how can you use it in javascript?

Example:

I have a simple form with several text boxes in it in a PHP page.
Textboxes are named like this:

txtbx[1], txtbx[2],.....

<input type=text size=3 name=txtbx[1] value=5>



how can I read their value with javascript?

normally it would be form.txtbx1.value
but the square bracket (for array in PHP) is causing problem.


thanks in advance

You can use form["txtbx[1]"].value to get the value.

1000000 thanks iBeZi.

Update:
I have tried using this method. Sometimes it works perfectly and sometimes it does not work altough conditions are similar if not identical.
Are there conditions involved in using this?
Can you suggest a link or article to do some reading on this topic.
Thanks in advance