0.25_regular_expressions_elements_regexp_group.js

// There are four kinds of groups

// Capturing:
// A capturing group is a regexp choice wrapped in parentheses. The characters
// that match the group will be captured. Every capture group is given a number.
// The first capturing ( in the regular expression is group 1. The second capturing (
// in the regular expression is group 2

// Noncapturing
// A noncapturing group has a (?: prefix. A noncapturing group simply matches; it
// does not capture the matched text. This has the advantage of slight faster performance. Noncapturing groups do not interfere with the numbering of capturing
// groups.

// Positive lookahead
// A positive lookahead group has a (?= prefix. It is like a noncapturing group
// except that after the group matches, the text is rewound to where the group
// started, effectively matching nothing. This is not a good part.

// Negative lookahead
// A negative lookahead group has a (?! prefix. It is like a positive lookahead
// group, except that it matches only if it fails to match. This is not a good part.