how to capture textarea events when character data is entered

how to capture textarea events when character data is entered

I'm having problems capturing any events from a textarea as I type a particular data string (++) into it. 

My ultimate goal is to produce a popup whenever two plus-signs (++) are entered into the textarea and some data has already been read from the server. The data read from the server will be displayed in another textarea in the popup, for further editing, and then redisplayed in another readonly texarea on the main screen, associated with the popup.

The original textarea is defined like this:

<textarea id="parameters" rows="2" cols="50" ></textarea>

and I've tried capturing the entry of data into it the following ways(the code is approximate, so if there are errors please pardon them):

jq = jQuery

jq('#parameters').change(function(event){alert});
jq('#parameters').on('change keypress paste',function(event){alert});

I have tried these as well as a couple other variations that I cannot recall, at the moment, and I'm not getting any events to fire consistently all the time, as I enter data.

Any help or suggestions would be greatly appreciated.

Thanks.