如何检查最后一个动态添加的元素是什么并运行特定功能

I am trying to write a code for a chat application. What I want is, When someone types something and clicks on send, I want to add a 'row' (dynamically) inside a container called 'chat'. The 'row' contains the message in another container called 'message' (which is also created dynamically). I was able to do that. But what I want to do is this, when someone types two message in a row (i mean before getting any reply from the person he/she is chatting with) and hits send I don't want add an entire 'row' in the 'chat'. I just want to append the 'message' inside the row, something like :I am trying to write a code for a chat applicat