1. document.getElementById(id-name)
2. document.getElementsByClassName(class-name)
3. document.getElementsByTagName(tag-name);
4. d.getElementsByName(name-attribute name);
Example
<!DOCTYPE html>
<html lang='en' xmlns='http://www.w3.org/1999/xhtml'>
<head>
<meta charset='utf-8' />
<title></title>
</head>
<body>
<p id='p2'></p>
<p class='p3'></p>
<p ></p>
<p name='p1'></p>
<script>
document.getElementById('p2').innerHTML = 'this is id selector';
var cls = document.getElementsByClassName('p3');
cls[0].innerHTML = 'class selector';
var tags = document.getElementsByTagName('p');
tags[2].innerHTML = ' this is tag name selector';
var names = document.getElementsByName('p1')[0];
names.innerHTML = 'this is name selector';
</script>
</body>
</html>
