我需要在正则表达式中逃脱破折号吗？ [英] Do I need to escape dash character in regex?
问题描述
我正在尝试理解短划线字符 - 需要使用正则表达式中的反斜杠进行转义吗？
I'm trying to understand dash character - needs to escape using backslash in regex?
考虑这一点：
var url = '/user/1234-username';
var pattern = /\/(\d+)\-/;
var match = pattern.exec(url);
var id = match[1]; // 1234
正如您在上面的正则表达式中所看到的，我正在尝试提取id的数量来自网址。我还使用反斜杠 \ 在我的正则表达式中转义 - 字符。但是当我删除那个反斜杠时，仍然很好....换句话说，这两个都很好：
As you see in the above regex, I'm trying to extract the number of id from the url. Also I escaped - character in my regex using backslash \. But when I remove that backslash, still all fine ....! In other word, both of these are fine:
/\/(\d+)\-//\/(\d+)-/
现在我想知道哪一个是正确的（标准）？我需要在正则表达式中逃脱破折号吗？
Now I want to know, which one is correct (standard)? Do I need to escape dash character in regex?
推荐答案
如果它可以被解释为范围指示器，你只需要转义破折号字符（里面可以是这种情况） 角色类）。
You only need to escape the dash character if it could otherwise be interpreted as a range indicator (which can be the case inside a character class).
/-/ # matches "-"
/[a-z]/ # matches any letter in the range between ASCII a and ASCII z
/[a\-z]/ # matches "a", "-" or "z"
/[a-]/ # matches "a" or "-"
/[-z]/ # matches "-" or "z"
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