freeCodeCamp/guide/english/certifications/front-end-libraries/redux/write-a-counter-with-redux/index.md

title
Write a Counter with Redux

Write a Counter with Redux

The goal of this challenge is to apply all the concepts learned from previous Redux challenges and create a simple counter that will increment or decrement a state by 1.

Hint 1

The best way to solve this challenge is by reviewing previous redux lessons particularly the following:

• Use const for Action Types
• Use a Switch Statement to Handle Multiple Actions
• Define an Action Creator
• Handle an Action in the Store
• Create a Redux Store

Solution

const INCREMENT = 'INCREMENT'; // define a constant for increment action types
const DECREMENT = 'DECREMENT'; // define a constant for decrement action types

// define the counter reducer which will increment or decrement the state based on the action it receives
const counterReducer = (state = 0, action) => {
    switch(action.type){
        case INCREMENT: 
            return state+=1;          

        case DECREMENT: 
            return state-=1;                
            
        default:
            return state;
    }
} ; 

// define an action creator for incrementing
const incAction = () => { 
    return {
        type: INCREMENT
    }
}; 

// define an action creator for decrementing
const decAction = () => { 
    return {
        type: DECREMENT
    }
}; 

// define the Redux store here, passing in your reducers
const store = Redux.createStore(counterReducer);