How do you create your state management in React JS?

Creating your own state management library for React involves understanding the principles of state management, handling state updates, and providing a way for React components to interact with the state. Below is a simplified example of how you might create a basic state management library for React. Please note that this is a minimalistic illustration, and real-world state management libraries are more complex.

// CustomStateProvider.js
import React, { createContext, useContext, useReducer } from 'react';

// Create a context to hold the state and dispatch function
const CustomStateContext = createContext();

// Define a reducer function to handle state updates
const customStateReducer = (state, action) => {
  switch (action.type) {
    case 'SET_VALUE':
      return { ...state, value: action.payload };
    default:
      return state;
  }
};

// CustomStateProvider component that wraps your app
export const CustomStateProvider = ({ children }) => {
  const [state, dispatch] = useReducer(customStateReducer, { value: '' });

  return (
    <CustomStateContext.Provider value={{ state, dispatch }}>
      {children}
    </CustomStateContext.Provider>
  );
};

// Custom hook to access the state and dispatch function
export const useCustomState = () => {
  const context = useContext(CustomStateContext);
  if (!context) {
    throw new Error('useCustomState must be used within a CustomStateProvider');
  }
  return context;
};

Now, you can use this state management library in your React components:

// ExampleComponent.js
import React from 'react';
import { useCustomState } from './CustomStateProvider';

const ExampleComponent = () => {
  const { state, dispatch } = useCustomState();

  const handleInputChange = (e) => {
    const newValue = e.target.value;
    dispatch({ type: 'SET_VALUE', payload: newValue });
  };

  return (
    <div>
      <input
        type="text"
        value={state.value}
        onChange={handleInputChange}
      />
      <p>Current Value: {state.value}</p>
    </div>
  );
};

export default ExampleComponent;

In this example, CustomStateProvider sets up a context provider with a reducer to manage the state. The useCustomState hook allows components to access the state and dispatch function. Components can then dispatch actions to update the state.

Keep in mind that this is a minimal example, and real-world state management libraries often include features like middleware, async actions, and more sophisticated state structures. If you plan to use this in production, you should consider additional features and thoroughly test your implementation. Additionally, you may want to explore existing state management solutions like Redux or Recoil, which are widely adopted in the React community.

The useContext hook is a React hook and is not available in vanilla JavaScript. It is specifically designed to be used with React functional components to access values from the React context API.

If you are working with React, here is a brief overview of how useContext works:

1. Create a Context: First, you need to create a context using the createContext function. This creates a context object that has a Provider and a Consumer.

   // ExampleContext.js
   import { createContext } from 'react';

   const ExampleContext = createContext();
   export default ExampleContext;

1. Wrap Components with a Provider: Wrap the part of your component tree where you want to share a common value with a Provider. The Provider takes a value prop, which will be the shared value.

   // App.js
   import React from 'react';
   import ExampleContext from './ExampleContext';

   const App = () => {
     return (
       <ExampleContext.Provider value={{ exampleValue: 'Hello from Context!' }}>
         {/* Your component tree */}
       </ExampleContext.Provider>
     );
   };

   export default App;

1. Use useContext in a Component: In any child component, you can use the useContext hook to access the shared value from the context.

   // ExampleComponent.js
   import React, { useContext } from 'react';
   import ExampleContext from './ExampleContext';

   const ExampleComponent = () => {
     const contextValue = useContext(ExampleContext);

     return (
       <div>
         <p>{contextValue.exampleValue}</p>
       </div>
     );
   };

   export default ExampleComponent;

In this example, useContext takes the ExampleContext as an argument and returns the current context value provided by the nearest ExampleContext.Provider ancestor in the component tree.

Again, keep in mind that useContext and the context API are specific to React, and you won't be able to use them in plain vanilla JavaScript. If you're looking for a global state management solution in vanilla JavaScript, you might need to implement your own custom solution or consider using other libraries/frameworks like Redux or MobX.