A good start,!
But using it there are some strange/buggy behaviours (tested in Firefox 59-0-2 64 Bit, having a server side listener on change).
E.g., the placeholder text creates big problems if it is there.
You can avoid it just by setting it to an empty string (“”).
Also, sometimes, having a listener on change on server side, when typing it makes a new line for every character, so the result is a text like this:
w
o
r
d
But the set of supported features is already impressive: image pasting, enumeration points…