Facebook注册表单电子邮件验证模式

Facebook registration form email validation pattern

本文关键字：验证 模式 电子邮件 表单 注册 注册表 Facebook      更新时间：2023-09-26

当搜索RegExp模式来验证Javascript中的电子邮件地址时，我发现了Facebook从这里使用的模式。

function is_email(a){return /^(['w!.%+'-])+@(['w'-])+(?:'.['w'-]+)+$/.test(a);}

谁能给我解释一下这个模式是如何工作的?我知道它正在寻找三个位置的"单词字符"以及"@"字符。但是一个好的解释会对我理解这个有很大帮助。

有两个网站(据我所知)，为正则表达式模式生成解释。

  • regex101.com用文字解释模式
  • regexper.com以图形方式显示

下面是我自己对这个模式的解释:

^        # anchor the pattern to the beginning of the string; this ensures that
         # there are no undesired characters before the email address, as regex
         # matches might well be substrings otherwise
(        # starts a group (which is unnecessary and incurs overhead)
  ['w!.%+'-]
         # matches a letter, digit, underscore or one of the explicitly mentioned
         # characters (note that the backslash is used to escape the hyphen
         # although that is not required if the hyphen is the last character)
)+       # end group; repeat one or more times
@        # match a literal @
(        # starts another group (again unnecessary and incurs overhead)
  ['w'-] # match a letter, digit, underscore or hyphen
)+       # end group; repeat one or more times
(?:      # starts a non-capturing group (this one is necessary and, because
         # capturing is suppressed, this one does not incur any overhead)
  '.     # match a literal period
  ['w'-] # match a letter, digit, underscore or hyphen
  +      # one or more of those
)+       # end group; repeat one or more times
$        # anchor the pattern to the end of the string; analogously to ^

所以，这将是一个稍微优化的版本:

/^['w!.%+'-]+@['w'-]+(?:'.['w'-]+)+$/
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