@fluentui/react-context-selector

What is @fluentui/react-context-selector?

@fluentui/react-context-selector is a package that provides optimized context selectors for React. It allows you to create context providers and consumers with fine-grained updates, ensuring that only the components that need to re-render do so, improving performance in large applications.

What are @fluentui/react-context-selector's main functionalities?

Creating a Context

This feature allows you to create a new context using the `createContext` function provided by the package.

const MyContext = createContext(null);

Using a Context Provider

This feature allows you to create a context provider that supplies the context value to its children. The `useMemo` hook is used to memoize the context value to avoid unnecessary re-renders.

const MyProvider = ({ children }) => {
  const value = useMemo(() => ({ /* some value */ }), []);
  return <MyContext.Provider value={value}>{children}</MyContext.Provider>;
};

Consuming Context with Selector

This feature allows you to consume context values using the `useContextSelector` hook, which takes a context and a selector function. This ensures that the component only re-renders when the selected value changes.

const MyComponent = () => {
  const selectedValue = useContextSelector(MyContext, context => context.someValue);
  return <div>{selectedValue}</div>;
};

Other packages similar to @fluentui/react-context-selector

react-redux

react-redux is a package that provides bindings for using Redux with React. It allows you to connect your React components to the Redux store and select specific pieces of state. Compared to @fluentui/react-context-selector, react-redux is more focused on state management with Redux, while @fluentui/react-context-selector is focused on optimizing context usage in React.

recoil

recoil is a state management library for React that provides a way to manage global state with atoms and selectors. It allows you to create fine-grained state dependencies and optimize re-renders. Compared to @fluentui/react-context-selector, recoil offers a more comprehensive state management solution, while @fluentui/react-context-selector is specifically designed for optimizing context usage.

zustand

zustand is a small, fast, and scalable state management library for React. It allows you to create global state stores and use selectors to optimize re-renders. Compared to @fluentui/react-context-selector, zustand provides a more general state management solution, while @fluentui/react-context-selector focuses on optimizing context usage within React.

README

@fluentui/react-context-selector

React useContextSelector() and useContextSelectors() hooks in userland.

Introduction

React Context and useContext() is often used to avoid prop drilling, however it's known that there's a performance issue. When a context value is changed, all components that are subscribed with useContext() will re-render.

useContextSelector is recently proposed. While waiting for the process, this library provides the API in userland.

Installation

NPM

npm install --save @fluentui/react-context-selector

Yarn

yarn add @fluentui/react-context-selector

Technical memo

React context by nature triggers propagation of component re-rendering if a value is changed. To avoid this, this library uses undocumented feature of calculateChangedBits. It then uses a subscription model to force update when a component needs to re-render.

Limitations

• In order to stop propagation, children of a context provider has to be either created outside of the provider or memoized with React.memo.
• <Consumer /> components are not supported.
• The stale props issue can't be solved in userland. (workaround with try-catch)

Related projects

The implementation is heavily inspired by:

• use-context-selector
• react-tracked