Javascript Regex只匹配一次出现，不多也不少
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Javascript Regex to match only a single occurrence no more or less
提问by Obinwanne Hill
I have a string like below:
我有一个像下面这样的字符串：
single-hyphen
I need to match the hyphen. However, I only want to match a single occurrence of the hyphen, no more or less.
我需要匹配连字符。但是，我只想匹配一次出现的连字符，不多也不少。
So the string above will return true, but the two below will be false:
所以上面的字符串将返回真，但下面的两个将是假的：
1. a-double-hyphen
2. nohyphen
How do I define a regex to do this?
我如何定义一个正则表达式来做到这一点？
Thanks in advance.
提前致谢。
回答by Anirudha
You can do this
你可以这样做
/^[^-]+-[^-]+$/
^depicts the start of the string
^描述字符串的开始
$depicts the end of the string
$描述字符串的结尾
[^-]+matches 1 to many characters except -
[^-]+匹配 1 到多个字符，除了 -
回答by Amadan
/^[^-]*-[^-]*$/
Beginning of string, any number of non-hyphens, a hyphen, any number of non-hyphens, end of string.
字符串的开头，任意数量的非连字符，一个连字符，任意数量的非连字符，字符串的结尾。
回答by jbabey
You could use a combination of indexOfand lastIndexOf:
你可以使用的组合indexOf和lastIndexOf：
String.prototype.hasOne = function (character) {
var first = this.indexOf(character);
var last = this.lastIndexOf(character);
return first !== -1 &&
first === last;
};
'single-hyphen'.hasOne('-'); // true
'a-double-hyphen'.hasOne('-'); // first !== last, false
'nohyphen'.hasOne('-'); // first === -1, false
回答by VisioN
Weird (and not a Regex)... but why not?
奇怪（而不是 Regex）......但为什么不呢？
2 === str.split("-").length;
