diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a1349680..a8ef74dcc 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,34 +1,57 @@
 class Chronometer {
   constructor() {
     // ... your code goes here
+    this.currentTime = 0;
+    this.intervalId = null;
+
   }
 
   start(callback) {
     // ... your code goes here
+    if (callback) {
+      this.intervalId = setInterval(() => {
+        this.currentTime += 1;
+        callback();
+      }, 1000)
+    } else {
+      this.intervalId = setInterval(() => {
+        this.currentTime += 1;
+      }, 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;
+    this.intervalId = null;
   }
 
   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 fb3a43ab4..836a64c74 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -15,14 +15,25 @@ const splitsElement = document.getElementById('splits');
 
 function printTime() {
   // ... your code goes here
+  printMinutes();
+  printSeconds();
 }
 
 function printMinutes() {
   // ... your code goes here
+  const min = chronometer.getMinutes();
+  const minToStr = chronometer.computeTwoDigitNumber(min);
+  minDecElement.textContent = minToStr[0];
+  minUniElement.textContent = minToStr[1];
 }
 
 function printSeconds() {
   // ... your code goes here
+  const sec = chronometer.getSeconds();
+  const secStr = chronometer.computeTwoDigitNumber(sec);
+  console.log(secStr)
+  secDecElement.textContent = secStr[0];
+  secUniElement.textContent = secStr[1];
 }
 
 // ==> BONUS
@@ -32,34 +43,67 @@ function printMilliseconds() {
 
 function printSplit() {
   // ... your code goes here
+  const li = document.createElement('li');
+  li.textContent = chronometer.split();
+  splitsElement.appendChild(li);
 }
 
 function clearSplits() {
   // ... your code goes here
+  splitsElement.innerHTML = '';
+
 }
 
 function setStopBtn() {
   // ... your code goes here
+  btnLeftElement.classList.add('stop');
+  btnLeftElement.textContent = 'STOP';
 }
 
 function setSplitBtn() {
   // ... your code goes here
+  btnRightElement.classList.add('split');
+  btnRightElement.textContent = 'SPLIT'
 }
 
 function setStartBtn() {
   // ... your code goes here
+  btnLeftElement.classList.remove('stop');
+  btnLeftElement.textContent = 'START';
+
 }
 
 function setResetBtn() {
   // ... your code goes here
+  btnRightElement.classList.remove('split');
+  btnRightElement.textContent = 'RESET';
 }
 
 // Start/Stop Button
 btnLeftElement.addEventListener('click', () => {
   // ... your code goes here
+  if (btnLeftElement.classList.contains('stop')) {
+    setStartBtn();
+    setResetBtn();
+    chronometer.stop();
+  } else {
+    setStopBtn();
+    setSplitBtn();
+    chronometer.start(printTime)
+  }
 });
 
 // Reset/Split Button
 btnRightElement.addEventListener('click', () => {
   // ... your code goes here
+  if (btnRightElement.classList.contains('split')) {
+    printSplit();
+  } else {
+    chronometer.reset();
+    minDecElement.textContent = '0';
+    milUniElement.textContent = '0';
+    secDecElement.textContent = '0';
+    secUniElement.textContent = '0';
+    clearSplits();
+  }
 });