这个问题比一眼看起来更难回答。

世界各地有大量的人正在寻找“统治他们所有”,但事实是,有大量的电子邮件提供商。

为什么? 根据 RFC: https://en.wikipedia.org/wiki/Email_address#RFC_specification。

The local-part of the email address may use any of these ASCII characters:

- uppercase and lowercase Latin letters A to Z and a to z;
- digits 0 to 9;
- special characters !#$%&'*+-/=?^_`{|}~;
- dot ., provided that it is not the first or last character unless quoted, and provided also that it does not appear consecutively unless quoted (e.g. John..Doe@example.com is not allowed but "John..Doe"@example.com is allowed);[6]
Note that some mail servers wildcard local parts, typically the characters following a plus and less often the characters following a minus, so fred+bah@domain and fred+foo@domain might end up in the same inbox as fred+@domain or even as fred@domain. This can be useful for tagging emails for sorting, see below, and for spam control. Braces { and } are also used in that fashion, although less often.
- space and "(),:;<>@[\] characters are allowed with restrictions (they are only allowed inside a quoted string, as described in the paragraph below, and in addition, a backslash or double-quote must be preceded by a backslash);
- comments are allowed with parentheses at either end of the local-part; e.g. john.smith(comment)@example.com and (comment)john.smith@example.com are both equivalent to john.smith@example.com.

A__z/J0hn.sm{it!}h_comment@example.com.co

如果你尝试这个地址我赌它将失败在所有的或大部分的regex发布在整个网络上. 但记住这个地址遵循RFC规则,所以它是公平有效的。

想象一下我的失望,因为我无法在任何地方注册与这些 regex 检查!!!

如何处理,是的?

"very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com

在这样做时,一个好做法是“重新输入您的电子邮件”输入,以避免用户输入错误,如果这对您来说不够,请添加一个提前提交的模型窗口,标题为“这是您的当前电子邮件吗?”然后用户输入的电子邮件在一个H2标签中,您知道,清楚地显示他们输入的电子邮件,然后一个“是的,提交”按钮。

谁使用 @pvl 解决方案,并希望它通过 ESLint Prefer 模板,那么这里是一个版本,我使用模板字母而不是字符集合。

validateEmail(email) {
    let sQtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
    let sDtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
    let sAtom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
    let sQuotedPair = '\\x5c[\\x00-\\x7f]';
    let sDomainLiteral = `\\x5b(${sDtext}|${sQuotedPair})*\\x5d`;
    let sQuotedString = `\\x22(${sQtext}|${sQuotedPair})*\\x22`;
    let sDomainRef = sAtom;
    let sSubDomain = `(${sDomainRef}|${sDomainLiteral})`;
    let sWord = `(${sAtom}|${sQuotedString})`;
    let sDomain = `${sSubDomain}(\\x2e${sSubDomain})*`;
    let sLocalPart = `${sWord}(\\x2e${sWord})*`;
    let sAddrSpec = `${sLocalPart}\\x40${sDomain}`; // complete RFC822 email address spec
    let sValidEmail = `^${sAddrSpec}$`; // as whole string

    let reValidEmail = new RegExp(sValidEmail);

    return reValidEmail.test(email);
}

這是從 http://codesnippets.joyent.com/posts/show/1917 偷走的

email = $('email');
filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (filter.test(email.value)) {
  // Yay! valid
  return true;
}
else
  {return false;}

使用常规表达式可能是最好的方式. 你可以在这里看到大量的测试(从<unk>取出)

const validateEmail = (email) => {
  return String(email)
    .toLowerCase()
    .match(
      /^(([^<>()[\]\\.,;:\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,}))$/
    );
};

下面是接受单码的常规表达式的例子:

const re =
  /^(([^<>()[\]\.,;:\s@\"]+(\.[^<>()[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i;

但是,请记住,我们不应该只依靠JavaScript验证,JavaScript可以轻松禁用,这也应该在服务器侧验证。

下面是行动中的上述例子:

所有电子邮件地址都包含一个“at”(即 @)符号。

email.includes('@')

或者,如果您需要支持 IE/older 浏览器:

email.indexOf('@') > 0

即使你能完全确定一个电子邮件是否是RFC合成有效,这不会告诉你它是否属于提供它的人。

要做到这一点,请发送验证消息。

以下是 Regex 认证:

没有 @(-) 和(.) 之前的空间字符不应该在 @ 之后聚集在一起 没有 @ 2 字符之后的特殊字符必须在 @ 电子邮件之前的长度不应该低于 128 字符

function validateEmail(email) {
var chrbeforAt = email.substr(0, email.indexOf('@'));
if (!($.trim(email).length > 127)) {
    if (chrbeforAt.length >= 2) {
        var re = /^(([^<>()[\]{}'^?\\.,!|//#%*-+=&;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
        //var re = /[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
        return re.test(email);
    } else {
        return false;
    }
} else {
    return false;
}
}