diff --git a/javascript/chronometer.js b/javascript/chronometer.js
index 7a1349680..6c06fe396 100644
--- a/javascript/chronometer.js
+++ b/javascript/chronometer.js
@@ -1,34 +1,43 @@
 class Chronometer {
   constructor() {
-    // ... your code goes here
-  }
+  this.currentTime = 0;
+  this.intervalId = null
+}
 
   start(callback) {
-    // ... your code goes here
+    this.intervalId = setInterval(() => {// se usa función flecha para referenciar al chronometer
+      this.currentTime += 1;
+      if (callback){ 
+        callback();
+      }
+      }, 1000); 
   }
 
-  getMinutes() {
-    // ... your code goes here
+  getMinutes() { //math floor redondea el valor de la opereción
+    return Math.floor(this.currentTime /60); // extraer minutos enteros
   }
 
-  getSeconds() {
-    // ... your code goes here
+  getSeconds() { // calcular segundos restantes de la función anterior
+    return Math.floor (this.currentTime%60);
   }
 
   computeTwoDigitNumber(value) {
-    // ... your code goes here
+    return("0" + value).slice(-2) // esta función devuelve 0 + el parametro y el slice lo que hace es que siempre devuelva dos digitos
   }
 
   stop() {
-    // ... your code goes here
+    clearInterval(this.intervalId);
   }
 
   reset() {
-    // ... your code goes here
+    this.currentTime = 0;
+    this.intervalId= null;
   }
 
-  split() {
-    // ... your code goes here
+  split() { // crear el diseño mm:ss creando dos contaste donde se llama los minutos y segundo previamente creados. Para combinarlos y devolverlos en forma de cadena
+    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..ea1fac166 100644
--- a/javascript/index.js
+++ b/javascript/index.js
@@ -13,16 +13,24 @@ const milDecElement = document.getElementById('milDec');
 const milUniElement = document.getElementById('milUni');
 const splitsElement = document.getElementById('splits');
 
-function printTime() {
-  // ... your code goes here
+function printTime() { // imprime los numeros de las funciones creadas en chonometro "getminute" "getseconds"
+  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
@@ -31,35 +39,58 @@ 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();
+  }
 });