replacing a text with "$$$", gives truncated result in Javascript

Question

var text="$$$ $$ $"; 
var dummy="hello world"; 
dummy.replace("world", text);

expected output:

hello $$$ $$ $

actual output:

hello $$ $ $

i don't understand why this is happening. kindly help. it doesn't seem to happen with other symbols though.

thanks

Questions seeking debugging help ("why isn't this code working?") must include the desired behavior, a specific problem or error and the shortest code necessary to reproduce it in the question itself. Questions without a clear problem statement are not useful to other readers. — thefourtheye, Mar 25 '15 at 11:17

score 2 · Answer 1 · edited May 23 '17 at 11:56

2

It's because $ has a special meaning in regular expressions, which replace uses.

See this question for more details: link

edited May 23 '17 at 11:56

Community

answered Mar 25 '15 at 11:26

doldt

Tim · Answer 2 · 2015-03-25T11:33:34.153

The short answer is "because that's how String.replace works".

The docs at Mozilla Development Network are helpful here:

The replacement string can include the following special replacement patterns:

And so forth.. (there's more replacement rules, but I'm not going to quote the whole MDN page)

So, if we change your sample to:

var text="$$ ($&) $"; 
var dummy="hello world"; 
dummy.replace("world", text);

We get as a result:

"hello $ (world) $"

In short $& (and other sequences like $1 and $'), mean special things, and the way you escape a plain $ is by preceding it with another $.

2 Answers2