use zerowidth spaces for emojis

app/javascript/mastodon/components/autosuggest_textarea.js

@@ -11,8 +11,8 @@ import classNames from 'classnames';
 const textAtCursorMatchesToken = (str, caretPosition) => {
   let word;
 
-  let left  = str.slice(0, caretPosition).search(/\S+$/);
-  let right = str.slice(caretPosition).search(/\s/);
+  let left  = str.slice(0, caretPosition).search(/[^\s\u200B]+$/);
+  let right = str.slice(caretPosition).search(/[\s\u200B]/);
 
   if (right < 0) {
     word = str.slice(left);

app/javascript/mastodon/reducers/compose.js

@@ -123,7 +123,7 @@ function removeMedia(state, mediaId) {
 
 const insertSuggestion = (state, position, token, completion) => {
   return state.withMutations(map => {
-    map.update('text', oldText => `${oldText.slice(0, position)}${completion} ${oldText.slice(position + token.length)}`);
+    map.update('text', oldText => `${oldText.slice(0, position)}${completion}\u200B${oldText.slice(position + token.length)}`);
     map.set('suggestion_token', null);
     map.update('suggestions', ImmutableList(), list => list.clear());
     map.set('focusDate', new Date());
@@ -135,7 +135,7 @@ const insertEmoji = (state, position, emojiData) => {
   const emoji = emojiData.native;
 
   return state.withMutations(map => {
-    map.update('text', oldText => `${oldText.slice(0, position)}${emoji} ${oldText.slice(position)}`);
+    map.update('text', oldText => `${oldText.slice(0, position)}${emoji}\u200B${oldText.slice(position)}`);
     map.set('focusDate', new Date());
     map.set('idempotencyKey', uuid());
   });