function verif(form) {
     //check that mandatory fields are filled in
     var alertmessage;
     var missing_info;
     missing_info = "false";
     alert_message = "You haven't filled :\n";

     if (form.name.value == "") {
        alert_message = alert_message + "\n- your name";
        missing_info = "true";
     }
        if (form.email.value == "") {
                alert_message = alert_message + "\n- your email address";
                missing_info = "true";
        } else {
                if ( !isEmail( form.email.value ) ) {
                        alert_message = alert_message + "\n- your email address";
                        missing_info = "true";
                }
        }
     if (form.phone.value == "") {
        alert_message = alert_message + "\n- your phone number";
        missing_info = "true";
     }
//     if (form.address.value == "") {
//        alert_message = alert_message + "\n- your address";
//        missing_info = "true";
//     }
     if (form.budget.value == "") {
        alert_message = alert_message + "\n- your budget";
        missing_info = "true";
     }
     if (form.question.value == "") {
        alert_message = alert_message + "\n- your question";
        missing_info = "true";
     }

     alert_message = alert_message + "\n\nWe need those informations to contact the owner of the house."
 
    if (missing_info == "true"){
       alert (alert_message);
    }
    else {
      //all OK, submit
      form.submit();
    }
  }

function isEmail(str) {
        // are regular expressions supported?
        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);
        else {
                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));
        }
}