The React model describes an application as a tree of “components”. Each component represents a subset of the complete UI element tree. For each component, there is a template function that takes some inputs and returns the new desired state of the UI. This function is called whenever an event occurs that might change the state of the UI. The template produces a data structure known as a “virtual DOM”. To realize this new state in the actual DOM, React diffs the previous tree with the new one and updates, creates, and deletes elements as necessary.With FRP, you describe your program as an acyclic graph of nodes that contain time-varying values. The actual value of any given node is determined by a function that maps the current values of some input nodes into an output value. The system is bootstrapped by handling a UI event and updating the appropriate root node, which kicks off a cascade of updates throughout the graph.