Syntax
document.JavaScript-Selector.innerHTML = new-data;
Eaxmple
<!DOCTYPE html>
<html lang='en' xmlns='http://www.w3.org/1999/xhtml'>
<head>
<meta charset='utf-8' />
<title>Inner HTML</title>
<style>
</style>
</head>
<body>
<span>Some Data : </span>
<input type='text' id='txt' placeholder='some data please' />
<button onclick='changeData()' >Change Data</button>
<p id='fill'></p>
<script>
function changeData() {
var data = document.getElementById('txt').value;
document.getElementById('fill').innerHTML += data;
}
</script>
</body>
</html>