function isEmail(str) {
  // are regular expressions supported?
  temp = str.split('@');
  if(temp.length > 2) return false;
  var supported = 0;
  if (window.RegExp) {
   var tempStr = "a";
   var tempReg = new RegExp(tempStr);
   if (tempReg.test(tempStr)) supported = 1;
  }
  if (!supported)
  return (str.indexOf(".") > 2) && (str.indexOf("@") > 0) ;

  var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");
  var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");
  return (!r1.test(str) && r2.test(str));
}
function check() { 
if(document.forms[0].Dfirstname.value=="")
{
alert("First name!");
document.forms[0].Dfirstname.focus();
return false;
}
if(document.forms[0].Dlastname.value=="")
{
alert("Last name!");
document.forms[0].Dlastname.focus();
return false;
}
if(document.forms[0].Dcompany.value=="")
{
alert("Company name!");
document.forms[0].Dcompany.focus();
return false;
}
if(document.forms[0].Dphone1.value=="")
{
alert("Phone number!");
document.forms[0].Dphone1.focus();
return false;
}
if(isNaN(document.forms[0].Dphone1.value))
{
alert("Check phone number!");
document.forms[0].Dphone1.focus();
return false;
}
if(document.forms[0].Demail.value=="")
{
alert("Email!");
document.forms[0].Demail.focus();
return false;
}
if(!isEmail(document.forms[0].Demail.value)){
alert("Check the Email field!");
document.forms[0].Demail.focus();
return false;
}
if(document.forms[0].Daddress1.value=="")
{
alert("Address!");
document.forms[0].Daddress1.focus();
return false;
}
open("","contpop","left=150,top=100,width=600,height=300");
return true;
}