Replace part of string that doesn't match regex

Question

I am attempting to replace parts of a string that don\'t match a regular expression pattern using JavaScript. This is functionally equivalent to using the <

Answer 1

If I understand you correctly, this should be one possible solution:

'aforementioned'.replace(new RegExp(pattern + '|.', 'gi'), function(c) {
    return c === pattern ? c : '*';
});

>> "*fore*********"