[js][database] synctree cleanup

lib/modules/database/reference.js

@@ -20,6 +20,7 @@ import {
 import INTERNALS from './../../internals';
 
 // track all event registrations by path
+let listeners = 0;
 
 /**
  * Enum for event types
@@ -70,7 +71,6 @@ export default class Reference extends ReferenceBase {
   constructor(database: Object, path: string, existingModifiers?: Array<DatabaseModifier>) {
     super(path, database);
     this._promise = null;
-    this._listeners = 0;
     this._refListeners = {};
     this._database = database;
     this._query = new Query(this, path, existingModifiers);
@@ -517,7 +517,7 @@ export default class Reference extends ReferenceBase {
    * @return {string}
    */
   _getRegistrationKey(eventType) {
-    return `$${this._database._appName}$${this.path}$${this._query.queryIdentifier()}$${this._listeners}$${eventType}`;
+    return `$${this._database._appName}$/${this.path}$${this._query.queryIdentifier()}$${listeners}$${eventType}`;
   }
 
   /**
@@ -528,7 +528,7 @@ export default class Reference extends ReferenceBase {
    * @private
    */
   _getRefKey() {
-    return `$${this._database._appName}$${this.path}$${this._query.queryIdentifier()}`;
+    return `$${this._database._appName}$/${this.path}$${this._query.queryIdentifier()}`;
   }
 
   /**
@@ -636,18 +636,16 @@ export default class Reference extends ReferenceBase {
     const eventRegistrationKey = this._getRegistrationKey(eventType);
     const registrationCancellationKey = `${eventRegistrationKey}$cancelled`;
     const _context = (cancelCallbackOrContext && !isFunction(cancelCallbackOrContext)) ? cancelCallbackOrContext : context;
+    const registrationObj = {
+      eventType,
+      ref: this,
+      path: this.path,
+      key: this._getRefKey(),
+      appName: this._database._appName,
+      eventRegistrationKey,
+    };
 
-    this._syncTree.addRegistration(
-      {
-        eventType,
-        ref: this,
-        path: this.path,
-        key: this._getRefKey(),
-        appName: this._database._appName,
-        registration: eventRegistrationKey,
-      },
-      _context ? callback.bind(_context) : callback,
-    );
+    this._syncTree.addRegistration(registrationObj, _context ? callback.bind(_context) : callback);
 
     if (isFunction(cancelCallbackOrContext)) {
       // cancellations have their own separate registration
@@ -661,7 +659,7 @@ export default class Reference extends ReferenceBase {
           key: this._getRefKey(),
           appName: this._database._appName,
           eventType: `${eventType}$cancelled`,
-          registration: registrationCancellationKey,
+          eventRegistrationKey: registrationCancellationKey,
         },
         _context ? cancelCallbackOrContext.bind(_context) : cancelCallbackOrContext,
       );
@@ -674,16 +672,17 @@ export default class Reference extends ReferenceBase {
       key: this._getRefKey(),
       appName: this._database._appName,
       modifiers: this._query.getModifiers(),
+      hasCancellationCallback: isFunction(cancelCallbackOrContext),
       registration: {
         eventRegistrationKey,
+        key: registrationObj.key,
         registrationCancellationKey,
-        hasCancellationCallback: isFunction(cancelCallbackOrContext),
       },
     });
 
     // increment number of listeners - just s short way of making
     // every registration unique per .on() call
-    this._listeners = this._listeners + 1;
+    listeners += 1;
 
     // return original unbound successCallback for
     // the purposes of calling .off(eventType, callback) at a later date
@@ -755,4 +754,3 @@ export default class Reference extends ReferenceBase {
     return INTERNALS.SyncTree;
   }
 }
-