Set readonly for input text
document.getElementById("ctrl_id").readOnly = true; //pay attention to the readOnly, it's case sensitive.
Set option to unable to select for select control:
<option value="Genre" disabled="disabled">Genre</option>
Set select control to disabled (it has no readonly property):
<select disabled="disabled"></select>
Add a new option to a select control, it works under firefox 2.x and IE 5.x:
function addOption(select_ctrl, option_value, option_text){
var ctrl = document.getElementById(selectctl);
if(ctrl == null)
return;
var doc = ctrl.ownerDocument;
if (!doc)
doc = ctrl.document;
var opt = doc.createElement('OPTION');
opt.value = option_value;
opt.text = option_text;
ctrl.options.add(opt, ctrl.options.length);
}
Delete an option from select control:
selectctl.options[selectctl.selectedIndex] = null;
Delete all options from select control:
selectctrl.options.length = 0;
Change the css for an object:
document.getElementById("ctrl_id").className="SHOWN";