Get the checkbox value is checked or not using Jquery

 $(document).ready(function () {
    $('#<%=chkValidateBabyName.ClientID%>').change(function () {
          if ($(this).is(":checked")) {
            alert("Check box checked");
          }
          else{
           alert("Check box un checked");
         }
    });
});

Include this code in document ready function. then you will get checkbox value when the check box value is changed..