Debouncing the LMS API calls

src/BaseAPI.js

@@ -912,6 +912,31 @@ export default class BaseAPI {
         'The storeData method has not been implemented');
   }
 
+  /**
+   * A debounce function to throttle calls to LMS commit API
+   *
+   * @param {function} func
+   * @param {number} wait
+   * @param {boolean} immediate
+   * @return {function(...[*]=)}
+   * @private
+   */
+  _debounce(func, wait, immediate = false) {
+    let timeout;
+    return function(...args) {
+      const later = () => {
+        timeout = null; // added this to set same behaviour as ES5
+        // eslint-disable-next-line no-invalid-this
+        if (!immediate) func.apply(this, args); // this is called conditionally, just like in the ES5 version
+      };
+      const callNow = immediate && !timeout;
+      clearTimeout(timeout);
+      timeout = setTimeout(later, wait);
+      // eslint-disable-next-line no-invalid-this
+      if (callNow) func.apply(this, args);
+    };
+  }
+
   /**
    * Send the request to the LMS
    * @param {string} url
@@ -919,15 +944,17 @@ export default class BaseAPI {
    * @return {object}
    */
   processHttpRequest(url: String, params) {
+    const debounced = this._debounce(
+        function(url, params, settings, error_codes) {
           const genericError = {
             'result': global_constants.SCORM_FALSE,
-      'errorCode': this.#error_codes.GENERAL,
+            'errorCode': error_codes.GENERAL,
           };
 
           let result;
-    if (!this.#settings.sendBeaconCommit) {
+          if (!settings.sendBeaconCommit) {
             const httpReq = new XMLHttpRequest();
-      httpReq.open('POST', url, this.#settings.asyncCommit);
+            httpReq.open('POST', url, settings.asyncCommit);
             try {
               if (params instanceof Array) {
                 httpReq.setRequestHeader('Content-Type',
@@ -935,12 +962,12 @@ export default class BaseAPI {
                 httpReq.send(params.join('&'));
               } else {
                 httpReq.setRequestHeader('Content-Type',
-              this.settings.commitRequestDataType);
+                    settings.commitRequestDataType);
                 httpReq.send(JSON.stringify(params));
               }
 
-        if (typeof this.settings.responseHandler === 'function') {
+              if (typeof settings.responseHandler === 'function') {
-          result = this.settings.responseHandler(httpReq);
+                result = settings.responseHandler(httpReq);
               } else {
                 result = JSON.parse(httpReq.responseText);
               }
@@ -951,7 +978,7 @@ export default class BaseAPI {
           } else {
             try {
               const headers = {
-          type: this.settings.commitRequestDataType,
+                type: settings.commitRequestDataType,
               };
               let blob;
               if (params instanceof Array) {
@@ -978,6 +1005,9 @@ export default class BaseAPI {
           }
 
           return result;
+        }, 5000);
+
+    return debounced(url, params, this.settings);
   }
 
   /**