Those are two different things. React, in its current form, requires classes or something class-like in order to implement stateful components with lifecycles.

Those are two different things. React, in its current form, requires classes or something class-like in order to implement stateful components with lifecycles. It also does not require that you handle data immutably - you can run `this.state.someArray.push(newValue); this.setState({someArray : this.state.someArray})`, and React will re-render just fine. However, React also pushes you in functional programming directions: render methods should be pure functions, performance optimizations with `shouldComponentUpdate` work best if you've handled data immutably, and so on. The React team also plans to investigate a "stateful functional component" API at some point after the React 16 release. It's also worth noting that React was not the only reason why classes were added to Javascript. There were hundreds of "pseudo-class" implementations out there already (all a little bit different than the others), and there was clearly enough demand for the concept to add it to the language in a standardized way. Meanwhile, Redux has definitely helped popularize the idea of updating data immutably. The array spread operator was already added in ES6, and the object spread operator is nearing finalization. No, the language doesn't have full-blown immutable data structures, but handling data immutably is absolutely possible. If you don't like dealing with immutable updates yourself, there's Immutable.js (as you said), or dozens of immutable update utility libraries. Particularly in the case of Redux, use of classes for data is discouraged because of the other constraints Redux asks you to follow. Plain serializable data is needed in order for time-travel debugging and persistence scenarios to work properly. Overall, your complaints are split across a couple things. Classes exist because some JS devs want to use them. Functional-style approaches exist because some devs want to use them. Languages like C# and C++ have been "everything and the kitchen sink" for a while now, supporting multiple different paradigms in one language - Javascript is now the same way.