select of checkboxes

[murfy]

I have a JS code to select elements in form (select all checkboxes of all messages), but it is not working and I cannot find why:

function sel() {
    with(document.form) {
        for(i=0;i<elements.length;i++) {
            thiselm = elements[i];
            if(thiselm.name.substring(0,3) == 'del')
                thiselm.checked = !thiselm.checked
        }
    }
}

Error message in Firebug:

elements is not defined:
for(i=0;i<elements.length;i++) {

 

I found working code on different page, but this code does not work for this page with messages:

http://paste.ofcode.org/nN2ijGpxjjwd4ABRCsHmLj

 

So I have no idea how to fix that. Can you help? Or do you know Jquery and can you give me simple code in Jquery to do it with shorter code? I think that could be faster solution than to solve this complicated function

 

Example html with messages (utf8):

http://paste.ofcode.org/nKa2KUmpLrT2dNtRYayMV3

 

And demo with the problem:

http://jsfiddle.net/eD4VL/

[cyberRobot]

You have two forms named "form". Try changing the name of the table which doesn't have the checkboxes.