diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a1349680..dadeb52db 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,33 +1,47 @@
 class Chronometer {
   constructor() {
+    this.currentTime = 0
+    this.intervalId = null
     // ... your code goes here
   }
 
   start(callback) {
+    this.intervalId = setInterval (() => {
+      this.currentTime++
+      if (callback) callback()
+    }, 1000)
     // ... your code goes here
   }
 
   getMinutes() {
+    return Math.floor(this.currentTime / 60)
     // ... your code goes here
   }
 
   getSeconds() {
+    return this.currentTime % 60
     // ... your code goes here
   }
 
   computeTwoDigitNumber(value) {
+    return value < 10 ? `0${value}` : `${value}`;
     // ... your code goes here
   }
 
   stop() {
+     clearInterval(this.intervalId)
     // ... your code goes here
   }
 
   reset() {
+    this.currentTime = 0
     // ... your code goes here
   }
 
   split() {
+    const minutes = this.computeTwoDigitNumber(this.getMinutes())
+    const seconds = this.computeTwoDigitNumber(this.getSeconds())
+    return `${this.computeTwoDigitNumber(this.getMinutes())}:${this.computeTwoDigitNumber(this.getSeconds())}`;
     // ... your code goes here
   }
 }
diff --git a/javascript/index.js b/javascript/index.js
index fb3a43ab4..5c007232b 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -14,14 +14,23 @@ const milUniElement = document.getElementById('milUni');
 const splitsElement = document.getElementById('splits');
 
 function printTime() {
+  printMinutes ()
+  printSeconds ()
+  printMilliseconds ()
   // ... your code goes here
 }
 
 function printMinutes() {
+  const minutes = chronometer.computeTwoDigitNumber(chronometer.getMinutes())
+  minDecElement.textContent = minutes[0];
+  minUniElement.textContent = minutes[1];
   // ... your code goes here
 }
 
 function printSeconds() {
+  const seconds = chronometer.computeTwoDigitNumber(chronometer.getSeconds())
+  secDecElement.textContent = seconds[0];
+  secUniElement.textContent = seconds[1];
   // ... your code goes here
 }
 
@@ -31,35 +40,65 @@ function printMilliseconds() {
 }
 
 function printSplit() {
+  const li = document.createElement('li')
+  li.textContent = chronometer.split()
+  splitsElement.appendChild(li)
   // ... your code goes here
 }
 
 function clearSplits() {
+  splits.innerHTML = ''
   // ... your code goes here
 }
 
 function setStopBtn() {
+  btnLeftElement.textContent = 'STOP'
+  btnLeftElement.classList.remove('start')
+  btnLeftElement.classList.add('stop')
   // ... your code goes here
 }
 
 function setSplitBtn() {
+  btnRightElement.textContent = 'SPLIT'
+  btnRightElement.classList.remove('reset')
+  btnRightElement.classList.add('split')
   // ... your code goes here
 }
 
 function setStartBtn() {
+  btnLeftElement.textContent = 'START'
+  btnLeftElement.classList.remove('stop')
+  btnLeftElement.classList.add('start')
   // ... your code goes here
 }
 
 function setResetBtn() {
+  btnRightElement.textContent = 'RESET'
+  btnRightElement.classList.remove('split')
+  btnRightElement.classList.add('reset')
   // ... your code goes here
 }
 
 // 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()
+    printTime()
+    clearSplits()
+  } else {
+    printSplit()
+  }
 });