how to disable all listbox in a form

Question

how to disable all listbox in a form

Answer 1

$('#formId select').attr('disabled', 'disabled');

Edit: oops, thought I saw a jquery tag. Anyway:-

for (i = 0; i < theform.length; i++) {
        var formElement = theform.elements[i];
        if (formElement.tagName === "SELECT") {
            formElement.disabled = true;
        }
}

Answer 2

Just to improve on Gavin's correct answer:

var selects = theform.getElementsByTagName("select");
for (i = 0; i < selects.length; i++) {
  selects[i].disabled = true;
}