Replace Last Match in Regex

Question

I have an autocomplete user-tagging system that fills in usernames that come after an @ symbol. I have this problem however, where I have two users with a matching substring. For example:

Tagging @billy and @b When a user fills in the @b tag with a user named (for example) @brendan, it'll replace the @billy tag. How do I go backwards and replace only the last tag?

Edit: this is my current solution, but it feels kludgy. Is there a way to do this just with RegEx?:

function tagUser (chosenUsername) {
  var userRegex = new RegExp('(^|\\s)@([' + lastUserTag() + ']*)$', 'gi');
  var caption = $("#example").val();
  var match = caption.match(userRegex);

  var lastMatch = match[match.length - 1];
  $("#example").val(caption.replace(lastMatch, " @" + chosenUsername));
}

Can you show us the code that does the replacement?

Explosion Pills
– Explosion Pills

2013-03-27 20:35:44 +00:00
Commented Mar 27, 2013 at 20:35 — Explosion Pills
– Explosion Pills, Commented Mar 27, 2013 at 20:35

anubhava · Accepted Answer · 2013-03-27 21:03:26Z

3

Not sure if I understood your problem entirely. However just to let you know you can use negative lookahead to replace only last matched text like this:

var str='@billy and @b';
str = str.replace(/@b\b(?!.*?@b\b)/, 'brendan');

edited Mar 27, 2013 at 21:03

answered Mar 27, 2013 at 20:51

anubhava

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2 Comments

AlexQueue Over a year ago

This worked great, but then you edited the '\b'. Can you explain what those are for?

anubhava Over a year ago

I added \b for word boundary just to avoid matching something like @samuals when you're actually matching @sam.

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