title: jQuery: How to check if a date input field in empty
body: <p>What I have right now.   </p>
  
  <pre><code>$('form input[name="birthDate"])').blur(function () {
        var dob = $("#dob").val();
        if(dob == "") {
          $("#dobAlert").show();
          $("#laba").attr("disabled", true);
        } else {
          $("#dobAlert").hide();
        }
      });
  </code></pre>
  
  <p>The #laba is a button that I want to disable if the input is empty.
  I know I can disable the button if I put <code>required</code> in the input tag. But the problem I have is that it doesn't show the alert.</p>
  
  <p><a href="http://jsfiddle.net/karateka11/p1y8tazr/" rel="noreferrer">Code here</a></p>