validating an array in javaScript

Hi there,

I have a form with a series of check boxes with the same name - availability[].   The square brackets makes it as an array of course  :-) .

In javaScript, I am trying to determine if at least one of the check boxes is checked, but my code is producing an error.  This is want I have:

bAvailable = false;

for(var i=0; i < document.volunteer_app("availability[]").length; i++){
 
    if (document.volunteer_app("availability[" + i + "]").checked)
        bAvailable = true;
}

the error occurs on the following line:
  
     if (document.volunteer_app("availability[" + i + "]").checked)

Any suggestions as to what is wrong with my code.

Thanks,

RCorr