javascript alert box

EE4216/EE5806 Internet Client-Server computing

The use of javascript alert box.

  function formSubmit() 
  {  
    window.event.returnValue =false;   
   //  To find out which radio button is selected                                

    var com;            
   if (myform.Command[0].checked)
       com = "Search";
   else if (myform.Command[1].checked)
       com = "Update"; 
  else if (myform.Command[2].checked)
      com = "Delete"; 
   //document.write(" Command is : " + com);

   while ( window.event.returnValue !=true) 
   {
      switch (com)               
      {
         case "Search": 
           if (myform.Lastname.value.length == 0) 
           {
              window.alert("Search Command : \nLast name is 
Missing! ");  
            return;                            
           }
             else
           window.event.returnValue =true;    
           break;        

          case "Update": 
            if (myform.Lastname.value.length == 0)
            {
              window.alert("Update Command: \nLast name is missing! Please Fill in!");     
              return;
           }
           else if (myform.Firstname.value.length == 0)
           {
               window.alert("Update Command : \nFirst Name name is missing! Retry!! ");
             return;
            }
            else if (myform.PhoneNum.value.length == 0)
            {
              window.alert("Update Command : \nPhone Number is missing! Try again!! ");                       
               return;
             }
            else 
              window.event.returnValue =true; 
              break;

        case "Delete": 
            if (myform.Lastname.value.length == 0)
            {                          
             window.alert("Delete Command :\n Last name is Missing! "); 
             return; 
            }
            else if (myform.Firstname.value.length == 0)
           { 
              window.alert("Delete Command :\n First Name name is missing! Retry!! "); 
              return;                  
            }  
            else
              window.event.returnValue =true;
              break;
          default:
           break;
         }  
     }  // while
 }