Let’s summarise here how to disable, enable, check, assign values and get selected values from your html document.
1
2
3
4
5
<select name="client.idClient" id="idClient">
<option value="1">CLIENT 1</option>
<option value="2">CLIENT 2</option>
<option value="3">CLIENT 3</option>
</select>
You can disable an element by setting the disabled attribute to disabled:
1
jQuery("#idClient").attr("disabled","disabled");
And enable the element by removing the disabled attribute:
1
jQuery("#idClient").removeAttr("disabled");
If the element is an input:
1
<input type="checkbox" id="yes"/>
then you have to [...]

