即使我们只需要渲染一个组件，所有组件都将在react-redux中渲染

Question

I'm not sure it is default behaviour or redux or something else but i found that on dispatching an action, this action traverse through all reducers(that's ok) but it also invoke the connect listener of every reducer that further resulting rendering of its component. This means on every dispatch, all component inside app state tree get rendered. Is this intentionally done by redux or i've done something wronge. Help me out to clarify this things.

Answer 1

In Redux , your state is global and handled by the redux, whenever you dispatch an action , you are just setting the global state. Your container comonents will receive the new state and reducer would work on them but your components wont be rerendered since previous state and next state would be same.

Only those components would be rendered whose mapStatetoProps result in a different result

Answer 2

This behavior is totally fine. See the React Docs for their virtual DOM concept:

React makes use of a virtual DOM , which is a descriptor of a DOM subtree rendered in the browser. This parallel representation allows React to avoid creating DOM nodes and accessing existing ones, which is slower than operations on JavaScript objects. When a component's props or state change, React decides whether an actual DOM update is necessary by constructing a new virtual DOM and comparing it to the old one. Only in the case they are not equal, will React reconcile the DOM, applying as few mutations as possible.

So you don't have to worry that every component will get re-rendered every time you dispatch an action.