refactor src/Utils/Emitter.js

- Make flow of logic more compact. It reduces 12 code lines.
- Use filter for simple element removal. Unless there are lots of elements, breaking a loop doesn't actually have practical benefit.
- More flexible. It would be easier to edit even if argument is changed
to option pack (json).

packages/tiptap/src/Utils/Emitter.js

@@ -10,7 +10,6 @@ export default class Emitter {
     return this
   }
 
-
   emit(event, ...args) {
     this._callbacks = this._callbacks || {}
     const callbacks = this._callbacks[event]
@@ -22,33 +21,22 @@ export default class Emitter {
     return this
   }
 
-  // Remove event listener for given event. If fn is not provided, all event
-  // listeners for that event will be removed. If neither is provided, all
-  // event listeners will be removed.
+  // Remove event listener for given event.
+  // If fn is not provided, all event listeners for that event will be removed.
+  // If neither is provided, all event listeners will be removed.
   off(event, fn) {
-    if (!this._callbacks || (arguments.length === 0)) {
+
+    if (!arguments.length) {
       this._callbacks = {}
-      return this
-    }
-
-    // specific event
-    const callbacks = this._callbacks[event]
-    if (!callbacks) {
-      return this
-    }
-
-    // remove all handlers
-    if (arguments.length === 1) {
-      delete this._callbacks[event]
-      return this
-    }
-
-    // remove specific handler
-    for (let i = 0; i < callbacks.length; i += 1) {
-      const callback = callbacks[i]
-      if (callback === fn) {
-        callbacks.splice(i, 1)
-        break
+    } else {
+      // event listeners for the given event
+      const callbacks = this._callbacks ? this._callbacks[event] : null
+      if (callbacks) {
+        if (fn) {
+          this._callbacks[event] = callbacks.filter(cb => cb !== fn) // remove specific handler
+        } else {
+          delete this._callbacks[event] // remove all handlers
+        }
       }
     }