Post MySql data into textarea while writing

I'm looking for a jQuery / Javascript / Angular expert able to do this simple script. While the user is typing a text if it is delimited by two equal signs (as * or @), jQuery sends a POST call to a PHP page in order to retrieve from a MySql database a text that will substitute what he wrote. The most important thing is that the replacement has to be smooth and not prevent the user to keep writing. You should use Summer Note ([login to view URL]) as editor. In the attached documents, the database table to search in and an example you can try.