我崩潰了，因為我無法在我的郵件列表表單中執行我的選擇的自定義驗證。我有另一個字段，可以在無效時進行驗證，但在選擇中它似乎不起作用。讓我告訴你我的代碼。function validate() {  var x = document.forms["mlist-form"]["EMAIL"].value;  if (x == "") {    document.getElementById("email-error").innerHTML = "Email Address is required.";    document.getElementById("email-error").style.display = "block";    return false;  }  document.getElementById("email-error").innerHTML = "Please enter a valid Email Address.";  document.getElementById("email-error").style.display = "block";}document.addEventListener('invalid', (function() {  return function(e) {    //prevent the browser from showing default error bubble / hint    e.preventDefault();    // optionally fire off some custom validation handler    // myValidation();  };})(), true);function countryError() {  var f = document.forms["mlist-form"]["COUNTRY"].value;  if (f = "") {    document.getElementById("country-error-label").innerHTML = "Country is required.";    document.getElementById("country-error-label").style.display = "block !important";    return false;  }}