diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a13496..a95dd28 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,37 +1,55 @@
 class Chronometer {
   constructor() {
     // ... your code goes here
+    this.currentTime = 0;
+    this.intervalId = null;
   }
 
   start(callback) {
     // ... your code goes here
+    this.intervalId = setInterval(() => {
+      this.currentTime++;
+      if (callback)
+        callback();
+    }, 1000)
   }
 
   getMinutes() {
     // ... your code goes here
+    return Math.floor(this.currentTime / 60);
   }
 
   getSeconds() {
     // ... your code goes here
+    return this.currentTime % 60;
   }
 
   computeTwoDigitNumber(value) {
     // ... your code goes here
+    let formattedNumber = (value < 10) ? '0' + value.toString() : value.toString();
+    return formattedNumber;
   }
-
   stop() {
     // ... your code goes here
+    if (this.intervalId !== null) {
+      clearInterval(this.intervalId);
+      this.intervalId = null;
+    }
+    clearInterval(this.intervalId)
   }
 
   reset() {
     // ... your code goes here
+    this.currentTime = 0;
   }
 
   split() {
     // ... your code goes here
+    const minute = this.computeTwoDigitNumber(this.getMinutes());
+    const second = this.computeTwoDigitNumber(this.getSeconds());
+    return `${minute}:${second}`;
   }
 }
-
 // The following is required to make unit tests work.
 /* Environment setup. Do not modify the below code. */
 if (typeof module !== 'undefined') {
diff --git a/javascript/index.js b/javascript/index.js
index fb3a43a..b7ec2ac 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -15,14 +15,22 @@ const splitsElement = document.getElementById('splits');
 
 function printTime() {
   // ... your code goes here
+  printMinutes();
+  printSeconds();
 }
 
 function printMinutes() {
   // ... your code goes here
+  let minute = chronometer.computeTwoDigitNumber(chronometer.getMinutes());
+  minDecElement.innerHTML = minute[0];
+  minUniElement.innerHTML = minute[1];
 }
 
 function printSeconds() {
   // ... your code goes here
+  let second = chronometer.computeTwoDigitNumber(chronometer.getSeconds());
+  secDecElement.innerHTML = second[0];
+  secUniElement.innerHTML = second[1];
 }
 
 // ==> BONUS
@@ -32,34 +40,69 @@ function printMilliseconds() {
 
 function printSplit() {
   // ... your code goes here
+  let split = chronometer.split();
+  let li = document.createElement('li');
+  li.className = 'split-list';
+  li.innerHTML = split;
+  splitsElement.appendChild(li);
 }
 
 function clearSplits() {
   // ... your code goes here
+  splitsElement.innerHTML = '';
 }
 
 function setStopBtn() {
   // ... your code goes here
+  btnLeftElement.innerHTML = 'STOP';
+  btnLeftElement.classList.remove('start');
+  btnLeftElement.classList.add('stop');
 }
 
 function setSplitBtn() {
   // ... your code goes here
+  btnRightElement.innerHTML = 'SPLIT';
+  btnRightElement.className = 'btn split';
 }
 
 function setStartBtn() {
   // ... your code goes here
+  btnLeftElement.innerHTML = 'START';
+  btnLeftElement.className = 'btn start';
 }
 
 function setResetBtn() {
   // ... your code goes here
+  btnRightElement.innerHTML = 'RESET';
+  btnRightElement.className = 'btn reset';
 }
 
 // Start/Stop Button
 btnLeftElement.addEventListener('click', () => {
   // ... your code goes here
+  console.log(btnLeftElement.className);
+  if (btnLeftElement.className === 'btn start') {
+    chronometer.start(printTime);
+    setStopBtn();
+    setSplitBtn();
+  }
+  else {
+    chronometer.stop();
+    setStartBtn();
+    setResetBtn();
+  }
 });
 
 // Reset/Split Button
 btnRightElement.addEventListener('click', () => {
   // ... your code goes here
+  console.log(btnRightElement.className);
+  if (btnRightElement.className === 'btn reset') {
+    chronometer.reset();
+    printTime();
+    clearSplits();
+  }
+  else {
+    printSplit();
+  }
 });