Javascript - 正则表达式访问多次出现
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/7280586/
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
Javascript - Regex access multiple occurrences
提问by Pierre de LESPINAY
I have this text
我有这个文字
txt = "Local residents o1__have called g__in o22__with reports...";
in which I need to get the list of numbers between each oand __
其中我需要获取每个o和之间的数字列表__
If I do
如果我做
txt.match(/o([0-9]+)__/g);
I will get
我会得到
["o1__", "o22__"]
But I'd like to have
但我想拥有
["1", "22"]
How can I do that ?
我怎样才能做到这一点 ？
回答by soldier.moth
See this question:
看到这个问题：
txt = "Local residents o1__have called g__in o22__with reports...";
var regex = /o([0-9]+)__/g
var matches = [];
var match = regex.exec(txt);
while (match != null) {
matches.push(match[1]);
match = regex.exec(txt);
}
alert(matches);
回答by jfriend00
You need to use .exec()on a regular expression object and call it repeatedly with the g flag to get successive matches like this:
您需要.exec()在正则表达式对象上使用并使用 g 标志重复调用它以获得连续匹配，如下所示：
var txt = "Local residents o1__have called g__in o22__with reports...";
var re = /o([0-9]+)__/g;
var matches;
while ((matches = re.exec(txt)) != null) {
alert(matches[1]);
}
The state from the previous match is stored in the regular expression object as the lastIndexand that's what the next match uses as a starting point.
前一个匹配的状态作为 存储在正则表达式对象中lastIndex，这就是下一个匹配用作起点的状态。
You can see it work here: http://jsfiddle.net/jfriend00/UtF6J/
你可以在这里看到它的工作：http: //jsfiddle.net/jfriend00/UtF6J/
Using the regexp this way is described here: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp/exec.
此处描述了以这种方式使用正则表达式：https: //developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp/exec。
回答by CaNNaDaRk
/o([0-9]+?)__/g
This should work. Click hereand search for "lazy star".
这应该有效。单击此处并搜索“懒惰之星”。
var rx = new RegExp( /o([0-9]+?)__/g );
var txt = "Local residents o1__have called g__in o22__with reports...";
var mtc = [];
while( (match = rx.exec( txt )) != null ) {
alert( match[1] );
mtc.push(match[1]);
}
Jek-fdrv pointed out in the comments, that if you call rx.test just before the while loop some results are skipped. That's because RegExp object contains a lastIndex field that keeps track of last match's index in the string. When lastIndex changes then RegExp keeps matching by starting from it's lastIndex value, therefore a part of the string is skipped. A little example may help:
Jek-fdrv 在评论中指出，如果您在 while 循环之前调用 rx.test，则会跳过某些结果。这是因为 RegExp 对象包含一个 lastIndex 字段，用于跟踪字符串中最后一个匹配项的索引。当 lastIndex 更改时，RegExp 会从它的 lastIndex 值开始保持匹配，因此会跳过一部分字符串。一个小例子可能会有所帮助：
var rx = new RegExp( /o([0-9]+?)__/g );
var txt = "Local residents o1__have called g__in o22__with reports...";
var mtc = [];
console.log(rx.test(txt), rx.lastIndex); //outputs "true 20"
console.log(rx.test(txt), rx.lastIndex); //outputs "true 43"
console.log(rx.test(txt), rx.lastIndex); //outputs "false 0" !!!
rx.lastIndex = 0; //manually reset lastIndex field works in Chrome
//now everything works fine
while( (match = rx.exec( txt )) != null ) {
console.log( match[1] );
mtc.push(match[1]);
}
