Get input from watch face

Is it possible to get input from watch face? Says tap on a region/button, prompt a text, and modify the content of watch face?

I tried (web):

var msg = prompt("Message", "Merry Xmas!");
if (msg != null) {
message = msg;

It just show the text “Merry Xmas!” but user cannot change the text. So msg is either null or “Merry Xmas!”.