JavaScript Basic Example

<!DOCTYPE html>
<html>
<head>
<title>JavaScript Coding Tutorial - TutsInsider</title>
<style>
  .main{
    padding: 10px;
  } 
  .main-heading{
    background: #333333;
    color: #ffffff;
    padding: 20px;
  }
  .main-paragraph{
    margin-top: -20px;
    padding: 20px;
    box-shadow: inset 0 0 3px 0 #2a73cc;
  }
  .main-button{
    padding: 5px 10px;
    border: none;
    border-radius: 5px;
    background: #333333;
    color: #ffffff;
    box-shadow: 0 0 3px 0 #333333;
    cursor: pointer;
  }
</style>
</head>
<body>
<div class="main">
<h2 class="main-heading">What Can JavaScript Do?</h2>
<div class="main-paragraph" id="demo">JavaScript can interact with HTML markup.</div>
<button type="button" id="change-btn" class="main-button">Click Me!</button>
</div>

<script>
function changeHTML(){
	document.getElementById("demo").innerHTML = "Hello JavaScript!";
}
var x = document.getElementById("change-btn");
x.addEventListener("click", changeHTML);
</script>

</body>
</html>