diff --git a/public/js/appChart.js b/public/js/appChart.js
index eb1329b8cac28ad54bdb4e3aca4064342ab5b8d4..55e84d7696718b008800207bc3cddba5f7d80190 100644
--- a/public/js/appChart.js
+++ b/public/js/appChart.js
@@ -8,8 +8,8 @@ const BASE_URL = "http://193.196.39.91:8080/frost-icity-tp31/v1.1";
 
 /**
  * Create URL to fetch the Observations corresponding to a provided Datastream
- * @param {*} datastreamID - integer representing the Datastream ID
- * @returns {String}
+ * @param {Number} datastreamID - Integer representing the Datastream ID
+ * @returns {String} URL string for fetching the Observations corresponding to a Datastream
  */
 const getObservationsUrl = function (datastreamID) {
   if (!datastreamID) return;
@@ -19,9 +19,9 @@ const getObservationsUrl = function (datastreamID) {
 
 /**
  * Create a temporal filter string for the fetched Observations
- * @param {*} dateStart - start date in YYYY-MM-DD format
- * @param {*} dateStop - stop date in YYYY-MM-DD format
- * @returns {String}
+ * @param {String} dateStart Start date in YYYY-MM-DD format
+ * @param {String} dateStop Stop date in YYYY-MM-DD format
+ * @returns {String} Temporal filter string
  */
 const createTemporalFilterString = function (dateStart, dateStop) {
   if (!dateStart || !dateStop) return;
@@ -46,8 +46,8 @@ const axiosGetRequest = axios.get(BASE_URL_OBSERVATIONS, {
 
 /**
  * Format the response from SensorThings API to make it suitable for heatmap
- * @param {*} obsArray - Response from SensorThings API as array
- * @returns {Array}
+ * @param {Array} obsArray Response from SensorThings API as array
+ * @returns {Array} Array of formatted observations suitable for use in a heatmap
  */
 const formatSTAResponseForHeatMap = function (obsArray) {
   const dataSTAFormatted = [];
@@ -72,8 +72,8 @@ const formatSTAResponseForHeatMap = function (obsArray) {
 
 /**
  * Draw a heatmap using Highcharts library
- * @param {*} obsArray - Response from SensorThings API
- * @returns {void}
+ * @param {Array} obsArray Response from SensorThings API
+ * @returns {Object} Highcharts library heatmap object
  */
 const drawHeatMapHC = function (obsArray) {
   Highcharts.chart("chart-heatmap", {
@@ -167,8 +167,8 @@ const drawHeatMapHC = function (obsArray) {
 
 /**
  * Convert the observations' phenomenonTime from an ISO 8601 string to Unix epoch
- * @param {*} obsArray - Response from SensorThings API as array
- * @returns {Array}
+ * @param {Array} obsArray Response from SensorThings API as array
+ * @returns {Array} Array of formatted observations suitable for use in a line chart
  */
 const formatSTAResponseForLineChart = function (obsArray) {
   const dataSTAFormatted = [];
@@ -182,8 +182,8 @@ const formatSTAResponseForLineChart = function (obsArray) {
 
 /**
  * Draw a line chart using Highcharts library
- * @param {*} obsArray - Response from SensorThings API
- * @returns {void}
+ * @param {Array} obsArray - Response from SensorThings API
+ * @returns {Object} Highcharts library line chart object
  */
 const drawLineChartHC = function (obsArray) {
   // Create the chart
@@ -217,7 +217,7 @@ const drawLineChartHC = function (obsArray) {
  * Follows "@iot.nextLink" links in SensorThingsAPI's response
  * Appends new results to existing results
  * @async
- * @param {Object} responsePromise - Promise object
+ * @param {Object} responsePromise Promise object
  * @returns {Object} - Object containing results from all the "@iot.nextLink" links
  */
 const followNextLink = function (responsePromise) {