Sample code for JS detecting whether input characters contain illegal characters

function checks(t){
   szMsg="[#_%&'/",;:=!^]";
   alertStr="";
   for(i=1;i<+1;i++){
    if(((i-1,i))>-1){
alertStr="Do not contain illegal characters such as [#_%&'/",;:=!^]";
     break;
    }
   }
   if(alertStr != ""){
    alert(alertStr);
    return false;
   }
   return true;
  }