function  checkForm(f){	

//firstname

	if(f.cs_firstname.value=="" || f.cs_firstname.value==null){

		window.alert(T_NAME_TYPE);

		f.cs_firstname.focus();

		return false;

	}

//lastname

	if(f.cs_lastname.value=="" || f.cs_lastname.value==null){

		window.alert(T_NAME_TYPE);

		f.cs_lastname.focus();

		return false;

	}

//email -1
var REGEX_EMAIL = /^(([\-\w]+)\.?)+@(([\-\w]+)\.?)+\.[a-zA-Z]{2,4}$/;
	if (!REGEX_EMAIL.test(f.cs_email.value)){

		window.alert(T_EMAIL_TYPE);

		f.cs_email.focus();

		return false;

	}

//time

	if(f.cs_phone.value=="" || isNaN(f.cs_phone.value)){

		window.alert(T_PHONE_TYPE);

		f.cs_phone.focus();

		return false;

	}

	return esnc_aform;

}