It depends on what kind of highlight do you want. Here you have an example of How I do validations including chosen required combo. Probably more info than you wanted, but I think that Without all is difficult to understand how does it works.
At first I use for validtion a class validate that I add or remove to elements when is necesarry. and I have the expecific CSS for chosen like this: select.validate:invalid+.chosen-container
so the full code will be:
/* CSS */
.validate:invalid, .validate:invalid+label,
select.validate:invalid+.chosen-container {
box-shadow: 0px 3px 0px -1px red;
background-color: #fdf0f0;
}
with this method:
function validateFields(formId) {
var dataIsValid = false;
var id = formId != '' && formId != undefined ? '#' + formId : ''
if(jQuery(id + ' :invalid').length > 0) {
jQuery(id + ' :valid').removeClass('validate');
jQuery(id + ' :invalid').addClass('validate');
openModal('invalidData');
} else {
jQuery(':valid').removeClass('validate');
dataIsValid = true;
}
return dataIsValid;
}
and this for validate any form:
if(validateFields('formId')) {
//TODO
}
This works fine with chosen for me