diff --git a/Sprint-3/alarmclock/alarmclock.js b/Sprint-3/alarmclock/alarmclock.js
index 6ca81cd3b..d9ce6a275 100644
--- a/Sprint-3/alarmclock/alarmclock.js
+++ b/Sprint-3/alarmclock/alarmclock.js
@@ -1,4 +1,64 @@
-function setAlarm() {}
+// need to set interval outside of setAlarm() so that every time the user clicks set alarm
+// the previous interval is deleted. Otherwise there will be overlapping intervals
+// if a user clicks on set alarm while an countdown is already active.
+let intervalId = null;
+
+function setAlarm() {
+ const alarmClockInput = document.getElementById("alarmSet");
+ const clockDisplay = document.getElementById("timeRemaining");
+ let secondsRemaining = parseInt(alarmClockInput.value, 10);
+
+ if (!isValidInput(secondsRemaining)) {
+ alert("please enter a valid positive integer!");
+ return;
+ }
+
+ clearInterval(intervalId);
+
+ // display immediately on click;
+ const minutes = Math.floor(secondsRemaining / 60);
+ const seconds = secondsRemaining % 60;
+ displayTime(minutes, seconds, clockDisplay);
+
+ intervalId = setInterval(() => {
+ secondsRemaining--;
+
+ if (secondsRemaining <= 0) {
+ clearInterval(intervalId);
+ displayTime(0, 0, clockDisplay);
+ playAlarm();
+ return;
+ }
+
+ const minutes = Math.floor(secondsRemaining / 60);
+ const seconds = secondsRemaining % 60;
+ displayTime(minutes, seconds, clockDisplay);
+ }, 1000);
+}
+
+// formats and displays countdown time to a supplied element
+function displayTime(mins, secs, elem) {
+ const minsFormatted = String(mins).padStart(2, "0");
+ const secsFormatted = String(secs).padStart(2, "0");
+ elem.textContent = `Time Remaining: ${minsFormatted}:${secsFormatted}`;
+}
+
+// returns true if input is an integer, false otherwise
+function isValidInput(input) {
+ if (input === "" || isNaN(input)) {
+ return false;
+ }
+
+ if (!Number.isInteger(input)) {
+ return false;
+ }
+
+ if (input < 0) {
+ return false;
+ }
+
+ return true;
+}
// DO NOT EDIT BELOW HERE
diff --git a/Sprint-3/alarmclock/index.html b/Sprint-3/alarmclock/index.html
index 48e2e80d9..89054f4b1 100644
--- a/Sprint-3/alarmclock/index.html
+++ b/Sprint-3/alarmclock/index.html
@@ -1,16 +1,16 @@
-
+
- Title here
+ Alarm clock app
Time Remaining: 00:00
-
+