New function: get timestamp of missing observations

Currently, this function is only available in the scope of the
function that formats observations for the scatter plot chart.

Get the timestamp of the observations that are available in the first
array but are missing from the second.

public/js/appChart.js

@@ -808,6 +808,44 @@ const formatSTAResponseForScatterPlot = function (obsArrayOne, obsArrayTwo) {
 
   console.log(obsArrayOneChecked.length);
   console.log(obsArrayTwoChecked.length);
+
+  // Create arrays with timestamps only
+  const obsArrayOneTimestamp = obsArrayOneChecked.map(
+    (obsTimeValue) => obsTimeValue[0]
+  );
+  const obsArrayTwoTimestamp = obsArrayTwoChecked.map(
+    (obsTimeValue) => obsTimeValue[0]
+  );
+
+  // console.log(obsArrayOneTimestamp);
+
+  /**
+   *
+   * @param {Array} obsTimestampArrayOne An array of timestamps for the first set of observations
+   * @param {Array} obsTimestampArrayTwo An array of timstamps for the second set of observations
+   * @returns {Array} An array of timestamps missing from the second set of observations
+   */
+  const getMissingTimestampFromSecondArray = function (
+    obsTimestampArrayOne,
+    obsTimestampArrayTwo
+  ) {
+    const differenceBetweenArrays = obsTimestampArrayOne.filter(
+      (timestampOne) => !obsTimestampArrayTwo.includes(timestampOne)
+    );
+    // .concat(
+    //   obsTimestampArrayTwo.filter(
+    //     (timestampTwo) => !obsArrayTwo.includes(timestampTwo)
+    //   )
+    // );
+
+    return differenceBetweenArrays;
+  };
+
+  const missingTimestamp = getMissingTimestampFromSecondArray(
+    obsArrayOneTimestamp,
+    obsArrayTwoTimestamp
+  );
+  console.log(missingTimestamp);
 };
 
 (async () => {