//Instant Validation with JavaScript-enabled WebDB
  //Listing 4

  //The JavaScript function isEmail checks whether the text entered in a field has a format 
  //appropriate for an e-mail address (xxxx@yyyy.zzzz or wwww.xxxx@yyyy.zzzz), displaying an 
  //error message and returning a value of “false” if it does not.

function isEmail(theElement, theName)
{
// This function checks if the text entered in a field has the 
// format xxxx@yyyy.zzzz.

 var email_regex = /^\w+\.{0,1}\w+@\w+\.\w+$/;

 if (!email_regex.test(theElement.value))
 {
  alert(theName + ": "+ 
     theElement.value + " is not a valid e-mail address");
  theElement.focus();
  return(false);
 }
 return(true);
}