Fix: Make sendState call async (Issue/134)

js/XAPI.js

@@ -65,6 +65,8 @@ class XAPI extends Backbone.Model {
       components: 'component',
       offlineStorage: 'offlineStorage'
     };
+
+    this.sendState = _.debounce(this.sendState.bind(this), 500);
   }
 
   /** Implementation starts here */
@@ -1086,10 +1088,9 @@ class XAPI extends Backbone.Model {
    * Sends the state to the or the given model to the configured LRS.
    * @param {AdaptModel} model - The AdaptModel whose state has changed.
    */
-  sendState(model, modelState) {
-    if (this.get('shouldTrackState') !== true || model.get('_isTrackable') === false) {
-      return;
-    }
+  async sendState(model, modelState) {
+    if (this.get('shouldTrackState') !== true) return;
+    if (model.get('_isTrackable') === false) return;
 
     const activityId = this.get('activityId');
     const actor = this.get('actor');
@@ -1102,7 +1103,7 @@ class XAPI extends Backbone.Model {
       return (o === type || o.indexOf(type) > -1);
     });
     const stateCollection = Array.isArray(state[collectionName]) ? state[collectionName] : [];
-    let newState;
+    let newState = modelState;
 
     if (collectionName !== 'course' && collectionName !== 'offlineStorage') {
       const index = _.findIndex(stateCollection, { _id: model.get('_id') });
@@ -1114,8 +1115,6 @@ class XAPI extends Backbone.Model {
       }
 
       newState = stateCollection;
-    } else {
-      newState = modelState;
     }
 
     // Update the locally held state.
@@ -1124,7 +1123,7 @@ class XAPI extends Backbone.Model {
       state
     });
 
-    // Pass the new state to the LRS.
+    // Pass the new state to the LRS
     this.xapiWrapper.sendState(activityId, actor, collectionName, registration, newState, null, null, (error, xhr) => {
       if (error) {
         Adapt.trigger('xapi:lrs:sendState:error', error);
@@ -1360,9 +1359,7 @@ class XAPI extends Backbone.Model {
    * @param {array} [attachments] - An array of attachments to pass to the LRS.
    */
   async sendStatement(statement, attachments = null) {
-    if (!statement) {
-      return;
-    }
+    if (!statement) return;
 
     Adapt.trigger('xapi:preSendStatement', statement);
 
@@ -1516,9 +1513,7 @@ class XAPI extends Backbone.Model {
    * @param {ADL.XAPIStatement[]} statements - An array of valid ADL.XAPIStatement objects.
    */
   async sendStatements(statements) {
-    if (!statements || statements.length === 0) {
-      return;
-    }
+    if (!statements || statements.length === 0) return;
 
     Adapt.trigger('xapi:preSendStatements', statements);