diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a13496..538649c 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,34 +1,50 @@
 class Chronometer {
   constructor() {
     // ... your code goes here
+    this.currentTime = 0;
+    this.intervalId = null;
   }
 
   start(callback) {
     // ... your code goes here
+    this.intervalId = setInterval(() => {
+      this.currentTime += 1;
+      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
+    return value < 10 ? `0${value}` : `${value}`;
   }
 
   stop() {
     // ... your code goes here
+    clearInterval(this.intervalId);
   }
 
   reset() {
     // ... your code goes here
+    this.currentTime = 0;
   }
 
   split() {
     // ... your code goes here
+    const minutes = this.computeTwoDigitNumber(this.getMinutes());
+    const seconds = this.computeTwoDigitNumber(this.getSeconds());
+    return `${minutes}:${seconds}`;
   }
 }
 
diff --git a/javascript/index.js b/javascript/index.js
index fb3a43a..cc54622 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -15,51 +15,96 @@ const splitsElement = document.getElementById('splits');
 
 function printTime() {
   // ... your code goes here
+  printMinutes();
+  printSeconds();
+  printMilliseconds();
 }
 
 function printMinutes() {
   // ... your code goes here
+  const minutes = chronometer.getMinutes();
+  const minutesString = chronometer.computeTwoDigitNumber(minutes);
+  minDecElement.textContent = minutesString[0];
+  minUniElement.textContent = minutesString[1];
+
 }
 
 function printSeconds() {
   // ... your code goes here
+  const seconds = chronometer.getSeconds();
+  const secondsString = chronometer.computeTwoDigitNumber(seconds);
+  secDecElement.textContent = secondsString[0];
+  secUniElement.textContent = secondsString[1];
 }
 
 // ==> BONUS
 function printMilliseconds() {
   // ... your code goes here
+  const milliseconds = chronometer.getMilliseconds();
+  const millisecondsString = chronometer.computeTwoDigitNumber(milliseconds);
+  milDecElement.textContent = millisecondsString[0];
+  milUniElement.textContent = millisecondsString[1];
 }
 
 function printSplit() {
   // ... your code goes here
+  const li = document.createElement('li');
+  li.className = 'split-item';
+  li.textContent = chronometer.split();
+  splitsElement.appendChild(li);
 }
 
 function clearSplits() {
   // ... your code goes here
+  splitsElement.innerHTML = '';
 }
 
 function setStopBtn() {
   // ... your code goes here
+  btnLeftElement.textContent = 'STOP';
+  btnLeftElement.className = 'btn stop';
 }
 
 function setSplitBtn() {
   // ... your code goes here
+  btnRightElement.textContent = 'SPLIT';
+  btnRightElement.className = 'btn split';
 }
 
 function setStartBtn() {
   // ... your code goes here
+  btnLeftElement.textContent = 'START';
+  btnLeftElement.className = 'btn start';
 }
 
 function setResetBtn() {
   // ... your code goes here
+  btnRightElement.textContent = 'RESET';
+  btnRightElement.className = 'btn reset';
 }
 
 // Start/Stop Button
 btnLeftElement.addEventListener('click', () => {
   // ... your code goes here
+  if(btnLeftElement.classList.contains('start')){
+    chronometer.start(printTime);
+    setStopBtn();
+    setSplitBtn();
+  } else {
+    chronometer.stop();
+    setStartBtn();
+    setResetBtn();
+  }
 });
 
 // Reset/Split Button
 btnRightElement.addEventListener('click', () => {
   // ... your code goes here
+  if(btnRightElement.classList.contains('reset')){
+    chronometer.reset();
+    clearSplits();
+    printTime();
+  } else {
+    printSplit();
+  }
 });