# 此页面贡献者：树

# email的正则正则正则

# 规范

传送门：https://tools.ietf.org/html/rfc5322#section-3.4.1

3.4.1. Addr-Spec Specification

An addr-spec is a specific Internet identifier that contains a locally interpreted string followed by the at-sign character ("@", ASCII value 64) followed by an Internet domain. The locally interpreted string is either a quoted-string or a dot-atom. If the string can be represented as a dot-atom (that is, it contains no characters other than atext characters or "." surrounded by atext characters), then the dot-atom form SHOULD be used and the quoted- string form SHOULD NOT be used. Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.

 Note: A liberal syntax for the domain portion of addr-spec is
 given here.  However, the domain portion contains addressing
 information specified by and used in other protocols (e.g.,
 [RFC1034], [RFC1035], [RFC1123], [RFC5321]).  It is therefore
 incumbent upon implementations to conform to the syntax of
 addresses for the context in which they are used.

addr-spec = local-part "@" domain

local-part = dot-atom / quoted-string / obs-local-part

domain = dot-atom / domain-literal / obs-domain

domain-literal = [CFWS] "[" *([FWS] dtext) [FWS] "]" [CFWS]

dtext = %d33-90 / ; Printable US-ASCII %d94-126 / ; characters not including obs-dtext ; "[", "]", or ""

The domain portion identifies the point to which the mail is delivered. In the dot-atom form, this is interpreted as an Internet domain name (either a host name or a mail exchanger name) as described in [RFC1034], [RFC1035], and [RFC1123]. In the domain- literal form, the domain is interpreted as the literal Internet address of the particular host. In both cases, how addressing is used and how messages are transported to a particular host is covered in separate documents, such as [RFC5321]. These mechanisms are outside of the scope of this document.

The local-part portion is a domain-dependent string. In addresses, it is simply interpreted on the particular host as a name of a particular mailbox.

大致翻译过来呢就是，邮箱地址分为三个部分，local-part、 @ 以及 domain。下面是 local-part 以及 domain 的详细规范：

# local-part

可以使用所有的 ASCII 字符，包括：

• 大小写字母
• 数字
• 特殊符号 !#$%&'*+-/=?^_`{|}~
• . 不可以放在开头或结尾或连续使用，除非用引号包括起来
• + 加号一般会被忽略
• 空格以及 "(),:;<>@[\] 只能包含在引号之内
• 注释可以包含在括号之内，例如 admin(el psy congroo)@geeku.net 等于 admin@geeku.net

除了上述的 ASCII 字符之外，U+007F 以上的 UTF-8 编码的字符按规范也可以使用，但可能会受到邮件系统的限制。

其他更为细节的规范可以参考维基百科中的介绍：维基百科:Email_address

# domain

domain 的命名规范很简单，即它得是个 hostname。domain 就是由一系列由点分隔的标签组成的。标签的命名规范如下：

• 大小写字母
• 数字，顶级域名不能是纯数字
• 连字符 -，连字符不可在开头或结尾

以上的规则被称为 LDH 规则 (letters, digits, hyphen)。

除了以上规则之外，domain 还可以是以 [] 包裹的 IP 地址。以括号包含的注释同样可以出现在 domain 中。

# 无脑版

const emailReg = /\w+@\w+\.\w+/;

# 优化(?)版

const emailReg = /[a-zA-Z0-9!#$%&'*+-/=?^_`{|}~]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-]{2}/;

# HTML5 之撒手不管版

<input type="email" />

# 谷歌搜到版

const emailReg = /^(([^<>()\[\]\\.,;:\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,}))$/;

# 参考

维基百科:Email_address