diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a13496..3b3d7d0 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,34 +1,51 @@
 class Chronometer {
   constructor() {
     // ... your code goes here
+    this.currentTime = 0;
+    this.intervalId = null;
   }
 
   start(callback) {
     // ... your code goes here
+    this.intervalId = setInterval(() => {
+      if (callback && typeof callback === 'function') {
+        callback();
+      }
+      this.currentTime++;
+    }, 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 ('00' + value).slice(-2);
   }
 
   stop() {
     // ... your code goes here
+    clearInterval(this.intervalId);
   }
 
   reset() {
     // ... your code goes here
+    this.currentTime = 0;
   }
 
   split() {
     // ... your code goes here
+    return(
+      this.computeTwoDigitNumber(this.getMinutes()) + ':' +
+      this.computeTwoDigitNumber(this.getSeconds())
+    );
   }
 }
 
diff --git a/javascript/index.js b/javascript/index.js
index fb3a43a..e84de5c 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -15,51 +15,87 @@ const splitsElement = document.getElementById('splits');
 
 function printTime() {
   // ... your code goes here
+  printMinutes();
+  printSeconds();
 }
 
 function printMinutes() {
   // ... your code goes here
+  let mm = chronometer.computeTwoDigitNumber(chronometer.getMinutes);
+  minDecElement.innerHTML = mm[0];
+  minUniElement.innerHTML = mm[1];
 }
 
 function printSeconds() {
   // ... your code goes here
+  let ss = chronometer.computeTwoDigitNumber(chronometer.getSeconds);
+  secDecElement.innerHTML = ss[0];
+  secUniElement.innerHTML = ss[1];
 }
 
 // ==> BONUS
 function printMilliseconds() {
   // ... your code goes here
+  // let ms = chronometer.computeTwoDigitNumber(chronometer.getMillieconds);
 }
 
 function printSplit() {
   // ... your code goes here
+  let split = chronometer.split();
+  let liTag = document.createElement('li');
 }
 
 function clearSplits() {
   // ... your code goes here
+  splitsElement.innerHTML = '';
 }
 
 function setStopBtn() {
   // ... your code goes here
+  btnLeftElement.innerHTML = 'STOP';
+  btnLeftElement.className = 'btn stop';
 }
 
 function setSplitBtn() {
   // ... your code goes here
+  btnLeftElement.innerHTML = 'SPLIT';
+  btnLeftElement.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
+  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
+  if (btnRightElement.className === 'btn reset') {
+    chronometer.reset();
+    printTime();
+    clearSplits();
+  } else {
+    printSplit();
+  }
 });