:disabled Selector
Selects all elements that are disabled.
.disabled()
As with other pseudo-class selectors (those that begin with a ":"), it is recommended to precede it with a tag name or some other selector; otherwise, the universal selector ("*") is implied. In other words, the bare $(':disabled') is equivalent to $('*:disabled'), so $('input:disabled') or similar should be used instead.
Although their resulting selections are usually the same, the :disabled selector is subtly different from the [disabled] attribute selector;:disabled matches elements that are actually disabled while [disabled] only checks for the existence of the disabled attribute.
The :disabled selector should only be used for selecting HTML elements that support the disabled attribute (<button>, <input>, <optgroup>, <option>, <select>, <textarea>, <menuitem>, and <fieldset>).
Finds all input elements that are disabled.
<form>
<input name="email" disabled="disabled" />
<input name="id" />
</form>
$("input:disabled").val("this is it");