I'm trying to implement word boundaries in my emoticons feature for a chat. But for some reason I can't seem to get the word boundaries to work. I am new to regex.

So when I do:

var reg = /\b\Hi\b/gi;
var str = 'HiHiHi Hi HiHiHi Hi';
alert(str.replace(reg, ''));

This happens: Jsfiddle

It actually works fine, and does remove those 2 Hi's that are standing alone.

But when I change the reg to an escaped smiley and then change the string:

var reg = /\b\:\)\b/gi;
var str = 'HiHi:) :) HiHiHi :)';
alert(str.replace(reg, ''));

This happens: Jsfiddle

It just doesn't work. The string stays the same. Is it that word boundaries can't be used on symbols? If so, how does Facebook do it on their chats?