Compare two form fields containing begin time and end time in AM PM format in a form

I have a simple question. I have a form called form2 that contains two fields. the Begin Time with id "s1Time1" and an End Time with id of "s1Time2". The two fields hold the formats of HH:MM AM or PM. All I need is to be able to tell in a javascript function that the Begin Time can not be greater than the End Time. I am not using any dates or seconds in my time fields.


This is what my form looks like:

<form id="form1" name="form1" method="post" action="">
  <div id="sample1" class="ui-widget-content" style="padding: .5em;">
    <p>
      <label>Start</label>
      <br/>
      <input name="s1Time1" id="s1Time1" value=""/>
      <br/>
      <label>End</label>
      <br/>
      <input name="s1Time2" id="s1Time2" value="" />
    </p>
    <p>
      <label></label>
     
    </p>
  </div>
  <input name="submitbtn" type="submit" id="submitbtn"  value="Submit" />
  </form>