JSX is a build step and is completely optional. If by "databinding stuff" you mean React's setState and friends, almost all of React's code deals with the actua

JSX is a build step and is completely optional. If by "databinding stuff" you mean React's setState and friends, almost all of React's code deals with the actual diffing and browser handling. Components are not much more than functions from props to a virtual DOM output. It's easy to use React without ever calling React.createClass (just pass the output of React.DOM to renderComponent). Still, we're looking at separating these parts of React so that you don't have to pay the file bytes but it's not a very significant difference right now anyway.