如何在JavaScript正则表达式中访问匹配的组？

我还没有将这些替代方法与之前在其他答案中提到的方法进行比较,但我怀疑这种方法的性能较差,而且其他方法的安全性较低.

你的语法可能不是最好的.FF/Gecko将RegExp定义为Function的扩展.
(FF2竟然typeof(/pattern/) == 'function')

这似乎是特定于FF - IE,Opera和Chrome都为它抛出异常.

相反,使用其他人先前提到的方法:RegExp#exec或String#match.
他们提供相同的结果:

var regex = /(?:^|\s)format_(.*?)(?:\s|$)/;
var input = "something format_abc";

regex(input);        //=> [" format_abc", "abc"]
regex.exec(input);   //=> [" format_abc", "abc"]
input.match(regex);  //=> [" format_abc", "abc"]

无需调用该exec方法!您可以直接在字符串上使用"match"方法.只是不要忘记括号.

var str = "This is cool";
var matches = str.match(/(This is)( cool)$/);
console.log( JSON.stringify(matches) ); // will print ["This is cool","This is"," cool"] or something like that...

位置0有一个包含所有结果的字符串.位置1具有由括号表示的第一个匹配,位置2具有在括号中隔离的第二个匹配.嵌套括号很棘手,所以要小心!

String#matchAll (see the Stage 3 Draft / December 7, 2018 proposal), simplifies acccess to all groups in the match object (mind that Group 0 is the whole match, while further groups correspond to the capturing groups in the pattern):

With matchAll available, you can avoid the while loop and exec with /g... Instead, by using matchAll, you get back an iterator which you can use with the more convenient for...of, array spread, or Array.from() constructs

This method yields a similar output to Regex.Matches in C#, re.finditer in Python, preg_match_all in PHP.

See a JS demo (tested in Google Chrome 73.0.3683.67 (official build), beta (64-bit)):

var myString = "key1:value1, key2-value2!!@key3=value3";
var matches = myString.matchAll(/(\w+)[:=-](\w+)/g);
console.log([...matches]); // All match with capturing group values

while ( ( match = myRegex.exec( myStr ) ) && matches.push( match[1] ) ) {};

console.log(arr[1]);  // prints: abc
console.log(arr[0]);  // prints:  format_abc

function getMatches(string, regex, index) {
  index || (index = 1); // default to the first capturing group
  var matches = [];
  var match;
  while (match = regex.exec(string)) {
    matches.push(match[index]);
  }
  return matches;
}


// Example :
var myString = 'Rs.200 is Debited to A/c ...2031 on 02-12-14 20:05:49 (Clear Bal Rs.66248.77) AT ATM. TollFree 1800223344 18001024455 (6am-10pm)';
var myRegEx = /clear bal.+?(\d+\.?\d{2})/gi;

// Get an array containing the first capturing group for every match
var matches = getMatches(myString, myRegEx, 1);

// Log results
document.write(matches.length + ' matches found: ' + JSON.stringify(matches))
console.log(matches);

const url =
  '/sf/ask/17360801/?some=parameter';
const regex = /(?https?):\/\/(?[\w-\.]*)\/(?[\w-\./]+)\??(?.*?)?$/;
const { groups: segments } = url.match(regex);
console.log(segments);