对于那些希望使用比破坏性的长达光年的RegEx匹配更好的可维护解决方案的人，我写了几行代码。那些想要节省字节的人，坚持使用RegEx变体:)

这种限制:

字符串中没有@ 字符串中没有点 @后面超过2个点 用户名中的错误字符(@之前) 字符串中超过2个@ 域内字符错误 子域字符错误 TLD中的坏字符 TLD -地址

无论如何，仍然有可能泄露，所以一定要将此与服务器端验证+电子邮件链接验证结合起来。

这是JSFiddle

 //validate email

var emailInput = $("#email").val(),
    emailParts = emailInput.split('@'),
    text = 'Enter a valid e-mail address!';

//at least one @, catches error
if (emailParts[1] == null || emailParts[1] == "" || emailParts[1] == undefined) { 

    yourErrorFunc(text);

} else {

    //split domain, subdomain and tld if existent
    var emailDomainParts = emailParts[1].split('.');

    //at least one . (dot), catches error
    if (emailDomainParts[1] == null || emailDomainParts[1] == "" || emailDomainParts[1] == undefined) { 

        yourErrorFunc(text); 

     } else {

        //more than 2 . (dots) in emailParts[1]
        if (!emailDomainParts[3] == null || !emailDomainParts[3] == "" || !emailDomainParts[3] == undefined) { 

            yourErrorFunc(text); 

        } else {

            //email user
            if (/[^a-z0-9!#$%&'*+-/=?^_`{|}~]/i.test(emailParts[0])) {

               yourErrorFunc(text);

            } else {

                //double @
                if (!emailParts[2] == null || !emailParts[2] == "" || !emailParts[2] == undefined) { 

                        yourErrorFunc(text); 

                } else {

                     //domain
                     if (/[^a-z0-9-]/i.test(emailDomainParts[0])) {

                         yourErrorFunc(text); 

                     } else {

                         //check for subdomain
                         if (emailDomainParts[2] == null || emailDomainParts[2] == "" || emailDomainParts[2] == undefined) { 

                             //TLD
                             if (/[^a-z]/i.test(emailDomainParts[1])) {

                                 yourErrorFunc(text);

                              } else {

                                 yourPassedFunc(); 

                              }

                        } else {

                             //subdomain
                             if (/[^a-z0-9-]/i.test(emailDomainParts[1])) {

                                 yourErrorFunc(text); 

                             } else {

                                  //TLD
                                  if (/[^a-z]/i.test(emailDomainParts[2])) {

                                      yourErrorFunc(text); 

                                  } else {

                                      yourPassedFunc();
}}}}}}}}}

<script type="text/javascript">
    $(document).ready(function() {
      $('.form_error').hide();
      $('#submit').click(function(){
           var name = $('#name').val();
           var email = $('#email').val();
           var phone = $('#phone').val();
           var message = $('#message').val();
           if(name== ''){
              $('#name').next().show();
              return false;
            }
            if(email== ''){
               $('#email').next().show();
               return false;
            }
            if(IsEmail(email)==false){
                $('#invalid_email').show();
                return false;
            }

            if(phone== ''){
                $('#phone').next().show();
                return false;
            }
            if(message== ''){
                $('#message').next().show();
                return false;
            }
            //ajax call php page
            $.post("send.php", $("#contactform").serialize(),  function(response) {
            $('#contactform').fadeOut('slow',function(){
                $('#success').html(response);
                $('#success').fadeIn('slow');
               });
             });
             return false;
          });
      });
      function IsEmail(email) {
        var regex = /^([a-zA-Z0-9_\.\-\+])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
        if(!regex.test(email)) {
           return false;
        }else{
           return true;
        }
      }
  </script>

<form action="" method="post" id="contactform">
                            <table class="contact-table">
                              <tr>
                                <td><label for="name">Name :</label></td>
                                <td class="name"> <input name="name" id="name" type="text" placeholder="Please enter your name" class="contact-input"><span class="form_error">Please enter your name</span></td>
                              </tr>
                              <tr>
                                <td><label for="email">Email :</label></td>
                                <td class="email"><input name="email" id="email" type="text" placeholder="Please enter your email" class="contact-input"><span class="form_error">Please enter your email</span>
                                  <span class="form_error" id="invalid_email">This email is not valid</span></td>
                              </tr>
                              <tr>
                                <td><label for="phone">Phone :</label></td>
                                <td class="phone"><input name="phone" id="phone" type="text" placeholder="Please enter your phone" class="contact-input"><span class="form_error">Please enter your phone</span></td>
                              </tr>
                              <tr>
                                <td><label for="message">Message :</label></td>
                                <td class="message"><textarea name="message" id="message" class="contact-input"></textarea><span class="form_error">Please enter your message</span></td>
                              </tr>
                              <tr>
                                <td></td>
                                <td>
                                  <input type="submit" class="contactform-buttons" id="submit"value="Send" />
                                  <input type="reset" class="contactform-buttons" id="" value="Clear" />
                                </td>
                              </tr>
                            </table>
     </form>
     <div id="success" style="color:red;"></div>

function validateEmail(emailaddress){  
   var emailReg = /^([\w-\.]+@([\w-]+\.)+[\w-]{2,4})?$/;  
   if(!emailReg.test(emailaddress)) {  
        alert("Please enter valid email id");
   }       
}

你应该看到:jquery.validate.js，把它添加到你的项目

这样使用它:

<input id='email' name='email' class='required email'/>

<!-- Dont forget to include the jQuery library here -->
<script type="text/javascript" src="jquery-1.3.2.min.js"></script>
<script type="text/javascript">

$(document).ready(function() {

    $("#validate").keyup(function(){

        var email = $("#validate").val();

        if(email != 0)
        {
            if(isValidEmailAddress(email))
            {
                $("#validEmail").css({
                    "background-image": "url('validYes.png')"
                });
            } else {
                $("#validEmail").css({
                    "background-image": "url('validNo.png')"
                });
            }
        } else {
            $("#validEmail").css({
                "background-image": "none"
            });         
        }

    });

});

function isValidEmailAddress(emailAddress) {
    var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i);
    return pattern.test(emailAddress);
}

</script>

<style>
    #validEmail
    {
        margin-top: 4px;
        margin-left: 9px;
        position: absolute;
        width: 16px;
        height: 16px;
    }

    .text
    {
        font-family: Arial, Tahoma, Helvetica;
    }
</style>

    <title>Live Email Validation with jQuery Demo</title>
</head>
<body>
    <div class="text"><h1>Reynoldsftw.com - Live Email Validation</h1><h2>Type in an email address in the box below:</h2></div>
    <div><input type="text" id="validate" width="30"><span id="validEmail"></span></div>
    <div class="text"><P>More script and css style

: www.htmldrive.net

来源:htmldrive.com

降落在这里……结果是这样的: https://html.spec.whatwg.org/multipage/forms.html#valid-e-mail-address

.．.它提供了以下正则表达式:

/^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/

.．.这要感谢jQuery验证插件自述文件上的注释: https://github.com/jzaefferer/jquery-validation/blob/master/README.md#reporting-an-issue

所以，@Fabian的答案的更新版本是:

function IsEmail(email) {
  var regex = /^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/;
  return regex.test(email);
}

希望这能有所帮助