diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a1349680..086aa1616 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,34 +1,47 @@
 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() { {
+    return Math.floor(this.currentTime / 60);
   }
 
-  getMinutes() {
-    // ... your code goes here
   }
 
   getSeconds() {
-    // ... your code goes here
+    return this.currentTime % 60;
   }
+  
 
   computeTwoDigitNumber(value) {
-    // ... your code goes here
+    return value.toString().padStart(2, '0');
   }
 
+
   stop() {
-    // ... your code goes here
+    clearInterval(this.intervalId);
+    this.intervalId = null;
   }
 
   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 fb3a43ab4..2a23a03d7 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -5,24 +5,27 @@ const btnLeftElement = document.getElementById('btnLeft');
 const btnRightElement = document.getElementById('btnRight');
 
 // get the DOM elements that will serve us to display the time:
-const minDecElement = document.getElementById('minDec');
-const minUniElement = document.getElementById('minUni');
-const secDecElement = document.getElementById('secDec');
-const secUniElement = document.getElementById('secUni');
-const milDecElement = document.getElementById('milDec');
-const milUniElement = document.getElementById('milUni');
-const splitsElement = document.getElementById('splits');
+const minDec = document.getElementById('minDec');
+const minUni = document.getElementById('minUni');
+const secDec = document.getElementById('secDec');
+const secUni = document.getElementById('secUni');
+const splits = document.getElementById('splits');
 
 function printTime() {
-  // ... your code goes here
+  printMinutes();
+  printSeconds();
 }
 
 function printMinutes() {
-  // ... your code goes here
+  const minutes = chronometer.computeTwoDigitNumber(chronometer.getMinutes());
+  minDec.innerText = minutes[0];
+  minUni.innerText = minutes[1];
 }
 
 function printSeconds() {
-  // ... your code goes here
+  const seconds = chronometer.computeTwoDigitNumber(chronometer.getSeconds());
+  secDec.innerText = seconds[0];
+  secUni.innerText = seconds[1];
 }
 
 // ==> BONUS
@@ -31,35 +34,58 @@ function printMilliseconds() {
 }
 
 function printSplit() {
-  // ... your code goes here
+  const splitTime = chronometer.split();
+  const li = document.createElement('li');
+  li.innerText = splitTime;
+  splits.appendChild(li);
 }
 
 function clearSplits() {
-  // ... your code goes here
+  splits.innerHTML = '';
 }
 
-function setStopBtn() {
-  // ... your code goes here
+function setStartBtn() {
+  btnLeftElement.innerText = 'START';
+  btnLeftElement.classList.remove('stop');
+  btnLeftElement.classList.add('start');
 }
 
-function setSplitBtn() {
-  // ... your code goes here
+function setStopBtn() {
+  btnLeftElement.innerText = 'STOP';
+  btnLeftElement.classList.remove('start');
+  btnLeftElement.classList.add('stop');
 }
 
-function setStartBtn() {
-  // ... your code goes here
+function setSplitBtn() {
+  btnRightElement.innerText = 'SPLIT';
+  btnRightElement.classList.remove('reset');
+  btnRightElement.classList.add('split');
 }
 
 function setResetBtn() {
-  // ... your code goes here
+  btnRightElement.innerText = 'RESET';
+  btnRightElement.classList.remove('split');
+  btnRightElement.classList.add('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();
+    printTime();
+    clearSplits();
+  } else {
+    printSplit();
+  }
+});
\ No newline at end of file