Javascript 正则表达式在不应该匹配逗号时匹配逗号

发布于 2024-12-11 18:10:45 字数 1058 浏览 0 评论 0原文

我无法弄清楚 Firefox 7.0.1 和 Google Chrome 14.0.835.202 中发生的这个 javascript 小奇怪现象（我没有测试过任何其他版本）。为什么 /[+-.]/g 除了匹配加号（+）、破折号（）之外，还匹配逗号（,） -）和句点（.）？

// Firebug
>>> "Hello, World++--..".match(/[+-.]/g);
[",", "+", "+", "-", "-", ".", "."]
>>> "Hello, World".match(/[+-.]/g);
[","]

// Chrome Developer Tools:
> "Hello, World++--..".match(/[+-.]/g);
  [",", "+", "+", "-", "-", ".", "."]
> "Hello, World".match(/[+-.]/g);
  [","]

好吧，也许我需要转义句点 (.)

// Firebug
>>> "Hello, World!".match(/[+-\.]/g);
[","]

// Chrome Developer Tools
> "Hello, World!".match(/[+-\.]/g);
  [","]

不。但是，如果我更改加号 (+) 和破折号 (-) 的顺序，它将停止匹配逗号 (,)。

// Firebug
>>> "Hello, World".match(/[-+.]/g);
null

// Chrome Developer Tools
> "Hello, World".match(/[-+.]/g);
  null

这对我来说毫无意义。 Firefox 和 Chrome 都共享相同的正则表达式错误，这似乎很奇怪。有人知道这是为什么吗？

原文

I cannot figure out this javascript little oddity that's occurs in Firefox 7.0.1 and Google Chrome 14.0.835.202 (I haven't tested any other versions). Why does /[+-.]/g match commas (,) in addition to plus signs (+), dashes (-) and periods (.)?

// Firebug
>>> "Hello, World++--..".match(/[+-.]/g);
[",", "+", "+", "-", "-", ".", "."]
>>> "Hello, World".match(/[+-.]/g);
[","]

// Chrome Developer Tools:
> "Hello, World++--..".match(/[+-.]/g);
  [",", "+", "+", "-", "-", ".", "."]
> "Hello, World".match(/[+-.]/g);
  [","]

Okay, so maybe I need to escape the period (.)

// Firebug
>>> "Hello, World!".match(/[+-\.]/g);
[","]

// Chrome Developer Tools
> "Hello, World!".match(/[+-\.]/g);
  [","]

Nope. But if I change the order of the plus (+) and dash (-) it stops matching the comma (,).

// Firebug
>>> "Hello, World".match(/[-+.]/g);
null

// Chrome Developer Tools
> "Hello, World".match(/[-+.]/g);
  null

This makes no sense to me. It seems odd that both Firefox and Chrome would share the same regex bug. Does anybody know why this is?

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献世佛 2024-12-18 18:10:45

使用[+\-.]。

- 屏蔽一个范围并且必须转义。

回复收藏 0 原文

遮了一弯 2024-12-18 18:10:45

在两个其他字符之间的方括号内使用 - 会匹配这些字符之间范围内的所有字符（包括这两个字符）。因此，+ 是 U+002B，. 是 U+002E。该范围内的所有字符都将包括：

+ U+002B
, U+002C
- U+002D
. U+002E

它与您包含的 3 个字符以及另外一个字符相匹配，这只是一个令人困惑的巧合。您的答案就在您的问题中...将 - 移至方括号中的第一个字符：

/[-+.]/g

或者，您可以转义 -：

/[+\-.]/g

Using - within square brackets between two other characters matches all characters in the range between those characters, inclusive. So, + is U+002B and . is U+002E. All of the characters in that range would include:

+ U+002B
, U+002C
- U+002D
. U+002E

That it was matching the 3 characters you included plus one more is just a confusing coincidence. Your answer is in your question... Move the - to be the first character in the square brackets: