checkbox - HTML5 Browser Validation for Checkboxes - given multiple checkboxes how can I make sure at-least one is selected? -

given simple this:

<form ...> <input type="checkbox" required name="op1"> option 1</u> <input type="checkbox" required name="op2"> option 2</u> <input type="submit"> </form> 

is there way using html5 validation validate if 1 of boxes checked , if none selected focus required tooltip on form?

you cannot html5 here way javascript

html

<form onsubmit="return checkcheckboxes(this);"> <input type="checkbox" required name="op1"> option 1</u> <input type="checkbox" required name="op2"> option 2</u> <input type="submit"> </form>   

javascript

 <script type="text/javascript" language="javascript">     <!--     function checkcheckboxes(theform) {         if (         theform.opt1.checked == false &&         theform.opt2.checked == false)          {             alert ('you didn\'t choose of checkboxes!');             return false;         } else {                 return true;         }     }     //-->     </script>