问题
Before React16, class components were used over functional components whenever there is a need to use state or lifecycle methods in your component.
In the latest release react introduced Hooks and Effects using which we can use state and lifecycle methods inside our functional components.
So is there any reason why still the class components exists? Is there any cases we still have to choose class components over functional
回答1:
Here you can see the cases where you will need class components
The most common case where you will need class components is if you want to make an ErrorBoundary, you will need a class component because you can't implement componentDidCatch with hooks... yet!
来源：https://stackoverflow.com/questions/56260982/react-class-components-vs-functional-components