javascript 非捕获组仍在比赛中显示
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/18178597/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
non-capture group still showing in match
提问by vin
I know this topic has been thoroughly covered on StackOverflow, but I can't for the life of me get my regular expression to work. So without further repetitive ado ...
我知道这个主题已经在 StackOverflow 上得到了彻底的介绍，但是我一生都无法让我的正则表达式起作用。所以没有进一步重复的麻烦......
This is what I have.
这就是我所拥有的。
String: <p model='cat'></p>
细绳： <p model='cat'></p>
Regex: .match(/(?:model=')(.*)(?:')/g)
正则表达式： .match(/(?:model=')(.*)(?:')/g)
This is what my expression returns: model='cat'
这是我的表达式返回的内容： model='cat'
This is what I want: cat
这就是我要的： cat
Why isn't my non capture group ignored? Is it that I don't understand what a non-capturing group does? Why isn't my Regex working?
为什么我的非捕获组没有被忽略？是不是我不明白非捕获组是做什么的？为什么我的正则表达式不起作用？
回答by Dallas
The entire match will always be group 0, you need to access that specific group (group 1 in this case since the first group is non-capture), you can do it like this:
整个比赛将始终是第 0 组，您需要访问该特定组（在本例中为第 1 组，因为第一组未捕获），您可以这样做：
var str = "<p model='cat'></p>";
var regex = /(?:model=')(.*)(?:')/g
var match = regex.exec(str);
alert(match[1]); // catAlso, I suppose you are probably wanting several matches within str, you could do that like this:
另外，我想您可能想要在 str 中进行多个匹配，您可以这样做：
var str = "<p model='cat'></p><p model='dog'></p><p model='horse'></p>";
var regex = /(?:model=')([^']*)/g
var matches = [];
var match;
while (match = regex.exec(str)) {
matches.push(match[1]);
}
alert(matches); // cat,dog,horse回答by JLRishe
A non-capturing group is basically a non-group ― a way to use parentheses without actually capturing that part of the pattern as a group.
非捕获组基本上是一个非组 - 一种使用括号而不实际将模式的那部分作为一个组捕获的方法。
It looks like what you're actually looking for are the "match prefix but exclude" group (?<=)and the "match suffix but exclude" group (?=).
看起来您实际上正在寻找的是“匹配前缀但排除”组(?<=)和“匹配后缀但排除”组(?=)。
If you use these, you get the desired result:
如果你使用这些，你会得到想要的结果：
var str = "<p model='cat'></p><p model='dog'></p><p model='horse'></p>";
var regex = /(?<=model=')[^']*(?=')/g
var matches = str.match(regex);
console.log(matches);