Question

what is the opposite function if the user unclicks a checkbox?

this is my script if the user clicks the checkbox

<script>
$(document).ready(function() {
  $("input[name$='INopt']").click(function() {
    $("#OUTsrvOtr").prop('class','text')
    });
});
</script>

 <input id="INsrv" name="INopt" type="checkbox" value="1" />1<br>

but i want this to run if the user unclicks/unchecks the checkbox

$("#OUTsrvOtr").prop('class','validate[required] text-input text')

Answer 1

Inside click method you can check if if checkbox is checked or unchecked

<script>
$(document).ready(function() {
  $("input[name$='INopt']").click(function() {
   if(this.checked){
        $("#OUTsrvOtr").prop('class','text');
     }
      else{
          $("#OUTsrvOtr").prop('class','validate[required] text-input text');
     }

    });
});
</script>