React createContext with useReducer TypeScipt

in this tutorial, I'll be exploring the React Context APIs for state management with useReudcer hook. we don't need to install any third-party library or some stuff, this is all the core feature. so let's right get into that!

First create a folder under src/ named state like so src/state. and then we need two files StateProvider.tsx, and reducer.ts.

now, write the below code inside StateProvider.tsx file

import React, { createContext, useContext, useReducer } from "react";
import { reducer, initialState, State } from "./reducer";

const AppContext = createContext<any>(null);

interface Props {
  children: JSX.Element | JSX.Element[];
}

export const StateProvider: React.FC<Props> = ({ children }) => (
  <AppContext.Provider value={useReducer(reducer, initialState)}>
    {children}
  </AppContext.Provider>
);

export const useStateValue = () => useContext(AppContext);

import the context API and wrapping the child components.

Reudcer.ts

export const actionTypes = {
  INCREMENT: "INCREMENT",
};

export interface State {
  count: number;
}

export const initialState: State = {
  count: 0,
};

export const reducer = (state = initialState, action: any) => {
  switch (action.Type) {
    case actionTypes.INCREMENT:
      return {
        ...state,
        count: state.count + action.count,
      };
    default:
      return state;
  }
};

creating reducer function and conditionally checking the Type.

Wrapping out

We need to wrap out the <App /> component so that we can access the state globally.

/src/index.tsx

  <React.StrictMode>
    <StateProvider>
      <App />
    </StateProvider>
  </React.StrictMode>,

Access and Dispatch

now you can access the state and dispatch it easily using the useStateValue function as a hook

import React from "react";
import { useStateValue } from "./state/StateProvider";
import { actionTypes } from "./state/reducer";
import "./App.css";

function App() {
  const [state, dispatch] = useStateValue();
  console.log(state);

  const incrementHandler = () => {
    dispatch({
      Type: actionTypes.INCREMENT,
      count: 1,
    });
  };

  return (
    <div className="App">
      <button onClick={incrementHandler}>Add +</button>
      <h2>{state.count}</h2>
    </div>
  );
}

export default App;

`

git repo: https://github.com/lifeeric/react-context-with-useReducer/tree/master

Thank

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Comments

[Andrew Baisden]

Cool and easy to read tutorial thanks for sharing.