function check()
  {
 
  if(document.getElementById('card1').value==1 && document.getElementById('card2').value==0)
  {
  var ret=Mod10(document.getElementById('card_no').value);
		if(ret==false)
		{
	   //alert("Enter valid credit card no.");
	   //document.getElementById('card_no').focus();
	   document.getElementById('card_no_err').innerHTML = 'Enter valid credit card no.';
	   return false;
		}
		else
		{
		document.getElementById('card_no_err').innerHTML = '';
		}
 }		
  if(document.f1.contact.value=='')
     {
     //alert("Please enter your contact name!");
	 document.getElementById('contact_err').innerHTML = 'Please enter your contact name!';
	 //document.f1.contact.focus();
	 return false;
     }
	 else
	 {
	 document.getElementById('contact_err').innerHTML = '';
	 }
	 <!-- var emailRegxp = /^([\w]+)(.[\w]+)*@([\w]+)(.[\w]{2,3}){1,2}$/; -->
	 <!--var emailRegxp = /^([\w]+)(.[\w]+)*@([\w]+)(.[\w]{2,4}){1,2}$/; -->
	  var emailRegxp =/^(['_a-z0-9-]+)(\.['_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,5})$/;
			var email=document.f1.email.value;
			if(emailRegxp.test(email) != true)
			{
				//alert("Email address appears to be incorrect");
				document.getElementById('email_err').innerHTML = 'Email address appears to be incorrect';
				//document.f1.email.select();
				//document.f1.email.focus();
				return false;
			}
			else
			{
			document.getElementById('email_err').innerHTML = '';
			}
			
	/*if(document.f1.ph1.value=='')
     {
	 document.getElementById('ph1_err').innerHTML = 'Please enter your Primary Phone number!';
	 return false;
     }
	 else
	 {
	 document.getElementById('ph1_err').innerHTML = '';
	 }*/
		
			
	  if(document.f1.ads.value=='')
     {
     //alert("Please enter your ADS name!");
	 document.getElementById('ads_err').innerHTML = 'Please enter your ADS name!';
	 //document.f1.ads.focus();
	 return false;
     }
	 else
	 {
	 document.getElementById('ads_err').innerHTML = '';
	 }
	 
	 
	 
	 
	 if(!document.f1.term_cond.checked)
     {
     //alert("Please enter your ADS name!");
	 document.getElementById('term_cond_err').innerHTML = 'Please accepted our terms and conditions!';
	 //document.f1.ads.focus();
	 return false;
     }
	 else
	 {
	 document.getElementById('term_cond_err').innerHTML = '';
	 }
	 
	 
  }