Question

In Jquery there is a regexp patten definition

var rvalidbraces = /(?:^|:|,)(?:\s*\[)+/g;

this pattern matches strings like “abc,[” and “abc:[“, but not for “abc^[“.
So what’s the meaning of this part in the pattern:

(?:^|:|,)

Answer 1

(?: ... ) is a group (like (...)) that doesn’t capture anything.

So your example (?:^|:|,) simply matches either the start of the text, a colon, or a comma.

this pattern matches strings like “abc,[” and “abc:[“, but not for “abc^[“.

It sounds like you don’t know what ^ means – in a regex, it means “the start of the string” (unless you’ve turned on multi-line mode, where it means “the start of the line”).