的Javascript電子郵件驗證

Question

我無法弄清楚什麼是缺少這樣當電子郵件是有效的，而跳過最後一個無效的消息，並移動到下一個項目的形式進行驗證：

enter code here 
    if (document.form1.email.value.length > 0) { 

    var tst = document.form1.email.value; 
    var okd = ['bankofamerica.com','baml.com','magner.com','ml.com','ust.com','ustrust.com'] 
    for (var i = 0; i < okd.length; i++) { okd[i] == okd[i].toLowerCase() } 

    var emailRE = /^[a-zA-Z0-9._+-]+@([a-zA-Z0-9.-]+\.[a-zA-Z]{2,4})$/ 
    var aLst = emailRE.exec(tst) 
    if (!aLst) { 
     alert(tst + ' is not a valid e-mail') 
    } else { 
     var sLst = aLst[1].toLowerCase() 
     for (var i = 0; i < okd.length; i++) { 
      if (sLst == okd[i]) { 
       // alert(aLst[1] + ' is allowed');--> 

      } 
     } 

      if (i == okd.length) alert(aLst[1] + ' is not allowed. Please enter an email address with an authorized domain.') 

      document.form1.email.select(); 
      return false; 


    } 
} 

Answer 1

我建議將此代碼放入一個函數中，可能名爲ValidateEmail()。

在您的循環中：如果您確定電子郵件有效，請致電return true;。這將阻止進一步的執行。如果該域不匹配，讓它繼續循環檢查其他域。

如果循環完成而沒有返回true，那麼您將知道它最後不匹配return false;。

編輯：使用try/catch語句來代替：

if (document.form1.email.value.length > 0) { 

    var tst = document.form1.email.value; 
    var okd = ['bankofamerica.com','baml.com','magner.com','ml.com','ust.com','ustrust.com'] 
    for (var i = 0; i < okd.length; i++) { okd[i] == okd[i].toLowerCase() } 

    try { 
     var emailRE = /^[a-zA-Z0-9._+-]+@([a-zA-Z0-9.-]+\.[a-zA-Z]{2,4})$/ 
     var aLst = emailRE.exec(tst) 

     if (!aLst) 
      throw (tst + ' is not a valid e-mail'); 

     // isValidDomain will be changed to 'true' only if it matches an item in the array 
     var isValidDomain = false; 

     var sLst = aLst[1].toLowerCase() 
     for (var i = 0; i < okd.length; i++) { 
      if (sLst == okd[i]) { 
       isValidDomain = true; 
       // We break here because a match has been found - no need to compare against the other domain names. 
       break; 
      } 
     } 

     if(!isValidDomain) 
      throw (aLst[1] + ' is not allowed. Please enter an email address with an authorized domain.'); 

     // If execution reaches here, you know it passed both tests! 
     return true; 

    } 
    catch(err) { 

     // This code block runs whenever an error occurs 

     alert(err); 
     document.form1.email.select(); 
     return false; 
    } 
} 

throw基本上就像一個goto命令。它將直接跳轉到代碼的catch(err)部分。大約嘗試，catch和throw

更多信息：

• http://www.w3schools.com/js/js_try_catch.asp
• http://www.w3schools.com/js/js_throw.asp

Answer 2

非常感謝您科林！

，我不得不刪除以下兩行，以避免在運行到下一個驗證領域阻止代碼：

   isValidDomain = true; 
        // We break here because a match has been found - no need to compare against the other domain names. 
        // break - exits code from running on down to next item on page 
       } 
      } 

      if (!isValidDomain) 
       throw (aLst[1] + ' is not allowed. Please enter an email address with an authorized domain.'); 

      // If execution reaches here, you know it passed both tests! 
     // return true; - was not needed, stops code from running on page 

     } 
     catch (err) {