javascript - 谁能告诉我为什么这个电子邮件验证不起作用？

Question

我正在尝试使电子邮件验证正常工作，但似乎无法找出问题所在。如果输入的电子邮件不是有效的电子邮件，我希望它发出警报。我附加的代码是电子邮件功能和电子邮件的表单代码。感谢您的帮助!

  {
            var emailfield=document.getElementById("emailaddress").value;  
            var atpos=emailfield.indexOf("@");  
            var dotpos=emailfield.lastIndexOf(".");  
            if (atpos<1 || dotpos<atpos+2 || dotpos+2>=emailfield.length){  
              alert("Please enter a valid email address with an @ and proper domain.")  
              return false;  

            }
            } 

这是表单的代码。

     <form action='#' method='post' name='f1' id="VPN" onsubmit='return checkButons(this)'> 


  Aspects <br>          
<input type='radio' name='aspect' id='aspect1' value='security' />Security <br>
 <input type='radio' name='aspect' id='aspect2'value='speed' /> Speed<br> 


  Features:<br> 

  <input type='checkbox' name='feat1' id='feat1'value='highspeedvpn' /> High Speed VPN <br> 
   <input type='checkbox' name='feat2' id='feat2' value='transactionguard' />Transaction Guard <br> 
      <input type='checkbox' name='feat3' id='feat3'value='antivirus' /> Antivirus Addon <br> 






        <h3 id="generaltext">Fill out your information below:</h3>

        <p>
        Name:<input name="Name"id='name'size=:50 type="text" required><br>
        </p> 
        <p>

        Email Address:<input name="Emailaddress"id='emailaddress'size=:50 type="text" required><br> 
        </p>
        <p>
        Street Address:<input name="S_Address"id='s_address'size=:50 type="text" required><br></p>
        <p>
        Address 2:<input name="Address_2"id='address_2'size=:50 type="text" required><br></p>      
        <p>
        Zip Code:<input name="Zip"id='zip'size=:50 type="text" required><br>  
        <p>
        City:<input name="City"id='city'size=:50 type="text" required><br>

Answer 1

您可以使用常规 exp 进行验证 -

var email = text_email.value;
    var re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    if (re.test(email)) {
        alert("Error msg");
        return false;
    }