This is a super simple demo for data joins in D3.js. It's the code companion of my tutorial Enter, Update, Exit – An Introduction to D3.js, The Web’s Most Popular Visualization Toolkit. If you're just getting started with D3 and want to get your head around one of its core principles, data joins, go check it out.
You can see the demo in action here.
And if you have questions, suggestions, or simply spotted a bug, please let me know!
–Christian