Add or subtract

First fiddle

by cmwlvip

HTML

<div class="counter" id="counter">0</div>
<button onclick="incrementCounter()">Increase</button>
<button onclick="decrementCounter()">Decrease</button>

CSS

.counter {
  font-size: 24px;
  text-align: center;
  margin-top: 50px;
}

button {
  padding: 10px 20px;
  font-size: 18px;
  cursor: pointer;
}

JavaScript

var counterValue = 0;
 var counterElement = document.getElementById('counter');

 function incrementCounter() {
   counterValue++;
   updateCounter();
 }

 function decrementCounter() {
   counterValue--;
   updateCounter();
 }

 function updateCounter() {
   counterElement.textContent = counterValue;
 }