Question

I want to match a separate word which starts with # character.

enter #code here - #code
some#string here - nothing
#test - #test

I came up with following regex:

   "enter #code here".replace(/\b#[\w]*/gi, "REPLACED") 

But it doesn’t work. After some testing i found that

   "enter #code here".replace(/#\b[\w]*/gi, "REPLACED") 

works just fine.

Now can someone explain why \b# part is incorrect in this case?

Thanks!

Answer 1

\b is a transition between a non-word character and a word character, or vice-versa. Because a '#' is not a word character, your first expression will only match a string that has a word character directly before the #.

What might work is the expression /(\W)#[\w]*/gi, because your second example will match any of those three strings. Use a backreference to put the non-word character from the match expression into the replacement.