gistfile1.js

>>> var clNode = document.getElementById('clExample');

>>> clNode.classList
// ['red', 'green', 'bold']

>>> clNode.classList.length
3

>>> clNode.classList.remove('bold')
// Now the classList is ['red', 'green']

>>> clNode.classList.add('emph')
// Now the classList is ['red', 'green', 'emph']

>>> clNode.classList.item(0)
red // classList.item takes an index.

>>> clNode.classList.contains('green')
true

>>> clNode.classList.toggle('green')
// Now the classList is ['red', 'emph']

>>> clNode.classList.toggle('green')
// Now the classList is ['red', 'green', 'emph']