Basic Dom Manipulation
document.querySelector('#easy').style.backgroundColor = "red";
document.querySelector('.container').style.backgroundColor = "blue";
document.querySelector('a').style.backgroundColor = "green";
document.querySelectorAll('a')[3].style.backgroundColor = "green";
document.querySelectorAll('a')[1].text = "Hello";
var p = document.createElement('p');
p.textContent = "This is a new paragraph";
p.style.fontSize = '16px';
li = document.querySelector('li');
a = li.firstElementChild;
li.insertBefore(p, a);
var a3 = document.querySelectorAll('a')[2];
a3.parentElement.removeChild(a3);
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</head>
<body>
<div class="container">
<h1 id="easy"> Welcome to my page</h1>
<h1>visitor</h1>
</div>
<ul>
<li><a href="#">Link1</a></li>
<li><a href="#">Link2</a></li>
<li><a href="#">Link3</a></li>
<li><a href="#">Link4</a></li>
</ul>
<script id="jsbin-javascript">
document.querySelector('#easy').style.backgroundColor = "red";
document.querySelector('.container').style.backgroundColor = "blue";
document.querySelector('a').style.backgroundColor = "green";
document.querySelectorAll('a')[3].style.backgroundColor = "green";
document.querySelectorAll('a')[1].text = "Hello";
var p = document.createElement('p');
p.textContent = "This is a new paragraph";
p.style.fontSize = '16px';
li = document.querySelector('li');
a = li.firstElementChild;
li.insertBefore(p, a);
var a3 = document.querySelectorAll('a')[2];
a3.parentElement.removeChild(a3);
</script>
<script id="jsbin-source-javascript" type="text/javascript">document.querySelector('#easy').style.backgroundColor = "red";
document.querySelector('.container').style.backgroundColor = "blue";
document.querySelector('a').style.backgroundColor = "green";
document.querySelectorAll('a')[3].style.backgroundColor = "green";
document.querySelectorAll('a')[1].text = "Hello";
var p = document.createElement('p');
p.textContent = "This is a new paragraph";
p.style.fontSize = '16px';
li = document.querySelector('li');
a = li.firstElementChild;
li.insertBefore(p, a);
var a3 = document.querySelectorAll('a')[2];
a3.parentElement.removeChild(a3);</script></body>
</html>