I want a contact form

function contactForm(name, email, phone, message) {
  var xhr = new XMLHttpRequest();
  var url = "https://formspree.io/your@email.com";
  var params = "name=" + name + "&email=" + email + "&phone=" + phone + "&message=" + message;
  xhr.open("POST", url, true);
  xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
  xhr.onreadystatechange = function () { 
      if (xhr.readyState == 4 && xhr.status == 200) {
          var return_data = xhr.responseText;
          if (return_data == "email_error") {
              alert("Please enter a valid email address");
          } else {
              alert("Thank you for contacting us, we will get in touch as soon as possible.");
              document.getElementById("contactform").innerHTML = "";
          }
      }
  }
  xhr.send(params);
}