refactor the whole damn thing

src/Util/NamedEventHandler.js

@@ -0,0 +1,28 @@
+export default class NamedEventHandler {
+  constructor () {
+    this._eventListener = {}
+  }
+  on (name, f) {
+    if (this._eventListener[name] == null) {
+      this._eventListener[name] = []
+    }
+    this._eventListener[name].push(f)
+  }
+  off (name, f) {
+    if (name == null || f == null) {
+      throw new Error('You must specify event name and function!')
+    }
+    let listener = this._eventListener[name] || []
+    this._eventListener[name] = listener.filter(e => e !== f)
+  }
+  emit (name, value) {
+    let listener = this._eventListener[name] || []
+    if (name === 'error' && listener.length === 0) {
+      console.error(value)
+    }
+    listener.forEach(l => l(value))
+  }
+  destroy () {
+    this._eventListener = null
+  }
+}