title: How to verify if checkbox is checked before proceeding?
body: <p>how do you check if a checkbox is checked when clicking submit?
  I want it to show an alert when the box is unchecked.</p>
  
  <p><a href="http://jsfiddle.net/tjE24/42/" rel="nofollow noreferrer">http://jsfiddle.net/tjE24/42/</a></p>
  
  <pre><code>$('#submit').on('click', function() {
       if($('#terms').is(':checked')) {
      }
      else {
       alert("To proceed you must accept the terms.")        
      }
   });
  </code></pre>