added exam timer. summary soon

index.html

@@ -89,4 +89,5 @@
 
     <script type="module" src="js/imports.js"></script>
     <script src="js/global.js" defer></script>
+    <script src="js/index.js" defer></script>
 </html>

js/index.js

@@ -0,0 +1,63 @@
+const title = document.getElementById("title");
+
+// This is for the AP exam timer.
+const examStart = new Date("May 3, 2023 12:00");
+const examEnd = new Date("May 3, 2023 15:15");
+
+const examElement = document.createElement("h3");
+if (title != undefined)
+{
+    // Add the newly created AP exam countdown element.
+    title.append(examElement);
+
+    // Enable the AP exam countdown.
+    updateCountdown();
+    setInterval(updateCountdown, 1000);
+}
+
+function updateCountdown()
+{
+    // Difference between now and the desired date in milliseconds.
+    const now = new Date(Date.now());
+    var mode = "waiting";
+
+    var difference = examStart - now;
+    if (difference < 0)
+    {
+        difference = examEnd - now;
+        mode = "doing";
+    }
+    if (difference < 0)
+    {
+        difference = -difference;
+        mode = "done";
+    }
+
+    // Get minutes and seconds from decimal hours.
+    var deciHours = difference / (1000 * 60 * 60);
+    var deciMinutes = (deciHours % 1) * 60;
+    var deciSeconds = (deciMinutes % 1) * 60;
+
+    var hours = Math.floor(deciHours);
+    var minutes = Math.floor(deciMinutes);
+    var seconds = Math.floor(deciSeconds);
+
+    // Construct string and assign it.
+    var string = `${hours}:${("0" + minutes).slice(-2)}:${("0" + seconds).slice(-2)}`;
+    switch (mode)
+    {
+        case "waiting":
+            string += " until the AP exam begins!";
+            break;
+
+        case "doing":
+            string += " until the AP exam ends!";
+            break;
+
+        case "done":
+            string += " since the AP exam has been completed!";
+            break;
+    }
+
+    examElement.textContent = string;
+}