createContext()

The createContext() function is used to create an instance of the Context API that other components can read. It should be used in combination with the useContext hook.

import { createContext } from 'react';

const MyContext = createContext(defaultValue);

• The defaultValue can either be another context made from the createContext() method or a primitive data type, including null.
• createContext() returns a context object that should be named in PascalCase.

To pass the context down further, it is necessary to wrap the component tree in a context provider. A value prop needs to be passed inside the provider.

export default function App() {
  const theme = 'light';

  return (
    <ThemeContext.Provider value={theme}>
      <Container />
    </ThemeContext.Provider>
  );
}

Components have to use the useContext() hook to get the context information.

Note: In legacy code, there may not only be Providers but also Consumers that wrap the components. This is no longer recommended.