regex - How do you access the matched groups in a JavaScript regular expression?

Question

I want to match a portion of a string using a regular expression and then access that parenthesized substring:

    var myString = "something format_abc"; // I want "abc"

    var arr = /(?:^|s)format_(.*?)(?:s|$)/.exec(myString);

    console.log(arr);     // Prints: [" format_abc", "abc"] .. so far so good.
    console.log(arr[1]);  // Prints: undefined  (???)
    console.log(arr[0]);  // Prints: format_undefined (!!!)

Answer 1

You can access capturing groups like this:

var myString = "something format_abc";
var myRegexp = /(?:^|s)format_(.*?)(?:s|$)/g;
var myRegexp = new RegExp("(?:^|s)format_(.*?)(?:s|$)", "g");
var match = myRegexp.exec(myString);
console.log(match[1]); // abc