Combo box validation in Javascript

 This is a very simple way to check empty or invalid values in php Combo Boxes. Simple yet functional. Simply copy and paste this script in,to your source code. This script is fully tested by me.

function ValidateCPA(calculate){

if (calculate.('cpa').chacked == false){
         alert ( "CPA Board Passer Information is required." );
         document.getElementById('cpa1').focus();
         return false;
         }
   
}