How can I programmatically reply to a Steemit post? Please review my Javascript code! :)

Target example: https://steemit.com/usa/@gaottantacinque/happy-4th-of-july

In the Dev Tools console:

This code fills the textarea but the button does not become enabled as it does instead simply clicking on the textarea and typing anything.

Also, the textarea value inserted programmatically disappears clicking for instance on the background but it does not when entered normally.

Thanks!

MY SOLUTION is posted on Stackoverflow: https://stackoverflow.com/questions/51216332/fill-and-submit-textarea-programmatically-in-javascript