// Initialize our submit flag to false
var formSubmitted=false;

function submitForm()
{
  //has the form been submitted before?
  if( formSubmitted == true )
  {
     alert("This form has already been submitted!!!");
     return false;
  }

  // Verify that all the data has been entered 
  if( verifyForm() == false )
  {
    alert ("Please complete the form before you submit it.");
    return false; // Don't submit
  }

  // Set the formSubmitted flag
  formSubmitted = true;

  // Show message to the user
  alert("The form has been submitted.\nThank you!");
 
  return true; // Submit form

}

function verifyForm()
{

  // Use this function to ensure that all the
  // required data has been entered in the form

  // return true if the form is complete
  // return false if its not

  return true;
}