title: MVC 5 - Validate a specific field on client-side
body: <p>I want to populate a city/state drop down list based on the postal code a user types into a textbox. So when the text changes, I'm going to make an ajax call to retrieve the data. However, I only want to perform that ajax request for valid postal codes. The field already validates using the DataAnnotations.RegularExpression attribute and jquery.validate.unobtrusive validation library. I'm unclear on what can and can't be used from jquery.validate when using unobtrusive. I've looked at the unobtrusive code, but haven't gotten an understanding of it yet. So two questions:</p>
  
  <p>Using javascript, </p>
  
  <ol>
  <li>is there a way to force validation on a specific field, not the whole form?</li>
  <li>is there a way to check whether a specific field is valid?</li>
  </ol>