What is the purpose of the passive (non-capturing) group in a Javascript regex?

Question

What is the purpose of the passive group in a Javascript regex?

The passive group is prefaced by a question mark colon: (?:group)

In other words

Answer 1

In addition to the answers above, if you're using String.prototype.split() and you use a capturing group, the output array contains the captured results (see MDN). If you use a non-capturing group that doesn't happen.

var myString = 'Hello 1 word. Sentence number 2.';
var splits = myString.split(/(\d)/);

console.log(splits);

Outputs:

["Hello ", "1", " word. Sentence number ", "2", "."]

Whereas swapping /(\d)/ for /(?:\d)/ results in:

["Hello ", " word. Sentence number ", "."]