用于长句子的Javascript RegExp
当我在电子邮件中使用getPlainBody()函数时，我试图删除系统信息。
我试着写一个regexp，但是这个对我来说太难了：
androidOS(v7.99.2)(android)(3593)(rev.136)(cbf87b2346eabe6ef)(6c72426bbc-151c-449c-a33d-3733234d404f)(SomeuserName23542)系统信息: Mi A1，
我试着.replace(/System+[a-zA-Z0-9._-]+)/gi,'')，但它给出了一个错误，我也尝试玩的第一部分和最后一部分，但似乎我只是不太明白规则。
回答 1
Stack Overflow用户
发布于 2018-08-10 22:52:12
更新
由于您已经声明需要删除所有以System info:开头并以7组带括号的字符串结尾的行，这对您来说应该是有效的：
.replace(/^(?:System info:)(?:[^(]+(?=\())?(?:\([^)]+\)){0,7}$/gim, '');该模式将匹配最多7组带括号的字符串(我不确定是否总是有7组，所以我将其视为上限)。
分解这种模式：
^ // start of line (multiline mode)
(?: // start non-capturing group
System info: // exactly match the literal text "System info:"
) // end non-capturing group
(?: // start non-capturing group
[^(] // match anything that is not a literal "("
+ // at least once, and as many times as possible
(?= // start positive lookahead group
\( // match a literal "("
) // end positive lookahead group
) // end non-capturing group
? // make it optional
(?: // start non-capturing group
\( // match a literal "("
[^)]+ // match anything that is not a literal ")"
\) // match a literal ")"
) // end non-capturing group
{0,7} // between exactly 0 and 7 times.
$ // end of line (multiline mode)You can test strings against the match here.
根据记录，+告诉RegEx引擎至少匹配它之前的任何内容一次，并且尽可能多次，贪婪地(这意味着引擎只会在绝对必要的情况下才会返回字符，以便进行整体匹配)。
原始
在不了解更多您想要的输出的情况下，我对您正在寻找的内容的最佳猜测是这样的(这可能需要一些解释)：
.replace(/^System info:[\w\d\s(),._-]+$/gim, '');分解一下..。
^ // start of line (in multiline mode)
System info: // exactly match the literal string "System info:"
[\w\d\s(),._-]+ // match any amount of characters that are either:
// "A" through "Z",
// or "a" through "z",
// or "0" through "9",
// or are whitespace,
// or a literal "(",
// or a literal ")",
// or a literal ",",
// or a literal ".",
// or a literal "_",
// or a literal "-",
$ // end of line (in multiline mode)You can test it here。另外，请注意正则表达式replace上的m标志，该标志打开多行模式，允许^在每行的开头匹配，而不是在整个字符串的开头匹配，并允许$在每行的结尾匹配，而不是在整个字符串的结尾匹配。
除非。您希望捕获信息(这会使正则表达式更加复杂)：
^(System(?:\s+)?info):(?:(?:(?:\s+)?((?:[\w\d._-]+)?(?:(?:\([\w\d.-]+\))+)?)?,?))+$当然，分解一下...
^ // start of line (in multiline mode)
( // start of first capture group
System // exactly match the string "System"
(?: // start a non-capturing group
\s+ // match any amount of whitespace
)? // end non-capturing group and make the whole thing optional
info // exactly match the string "info"
) // end of first capture group
: // exactly match the string ":"
(?: // start a non-capturing group
\s+ // match any amount of whitespace
)? // end non-capturing group and make the whole thing optional
( // start of second capture group
(?: // start a non-capturing group
[\w\d._-]+ // match any amount of characters that are either:
// "A" through "Z",
// or "a" through "z",
// or "0" through "9",
// or a literal ".",
// or a literal "_",
// or a literal "-",
)? // end non-capturing group and make the whole thing optional
(?: // start a non-capturing group
(?: // start a non-capturing group
\( // exactly match a literal "("
[\w\d.-]+ // match any amount of characters that are either:
// "A" through "Z",
// or "a" through "z",
// or "0" through "9",
// or a literal ".",
// or a literal "_",
// or a literal "-",
\) // exactly match a literal ")"
)+ // end non-capturing group and make the whole thing required
)? // end non-capturing group and make the whole thing optional
,? // exactly match a literal "," and make it optional
)+ // end second capture group and make the whole thing required
$ // end of line (in multiline mode)学习更多正则表达式的另一个很好的资源是https://www.regular-expressions.info/ (尽管我不相信那里有任何内置的沙箱，就像在https://regex101.com中那样)。
最后，正如Barmar和CertainPerformance在评论中正确地指出的那样，您尝试的.replace(/System+[a-zA-Z0-9._-]+)/gi,'')解决方案将不会工作，原因有两个：
- 结束
)未标记为文字字符(即\)或[)])，并且与开始的非文字(anywhere不匹配，这将导致错误。 -
System中+后面的m不会与System后面的空格匹配，但会与System匹配，或者匹配文字Syste后跟任意数量的m(例如Systemmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm).
https://stackoverflow.com/questions/51773798
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