React Native CountDown Timer | react-native-countdown-component

React Native Countdown Timer

This is an example of React Native Countdown Timer using react-native-countdown-component. A CountDown Timer is the reverse of the timer we usually see.  To make a CountDown Timer we will use CountDown component from react-native-countdown-component.

A countdown Timer can be used if you are making an App that has some time constraints like if you are making a quiz App, You need some sort of timer to show the remaining time. Let’s see the example below.

How to Make a Countdown Timer?

<CountDown
  until={this.state.totalDuration}
  //duration of countdown in seconds
  timetoShow={('H', 'M', 'S')}
  //formate to show
  onFinish={() => alert('finished')}
  //on Finish call
  onPress={() => alert('hello')}
  //on Press call
  size={20}
/>

In our example, we will make a CountDown Timer which will show the Count Down from the Expiry DateTime to the Current DateTime. If you want to make a simple quiz app using this you can directly pass the time for the CountDown Timer in seconds. We have used a library called moment which is very helpful if you are playing around the Date and Time.

To Make a React Native App

Getting started with React Native will help you to know more about the way you can make a React Native project. We are going to use react native command line interface to make our React Native App.

If you have previously installed a global react-native-cli package, please remove it as it may cause unexpected issues:

npm uninstall -g react-native-cli @react-native-community/cli

Run the following commands to create a new React Native project

npx react-native init ProjectName

If you want to start a new project with a specific React Native version, you can use the --version argument:

npx react-native init ProjectName --version X.XX.X

Note If the above command is failing, you may have old version of react-native or react-native-cli installed globally on your pc. Try uninstalling the cli and run the cli using npx.

This will make a project structure with an index file named App.js in your project directory.

Installation of Dependencies

To install dependencies open the terminal and jump into your project

cd ProjectName

1. To use CountDown you need to install react-native-countdown-component dependency.

To install this run the following command

npm install react-native-countdown-component --save

2. To use moment you need to install moment.

To install this run the following command

npm install moment --save

These commands will copy all the dependencies into your node_module directory. –save is optional, it is just to update the react-native-countdown-component and moment dependencies in your package.json file.

Code

Now Open App.js in any code editor and replace the code with the following code

App.js

// React Native CountDown Timer | react-native-countdown-component
// https://aboutreact.com/react-native-countdown-timer/

// import React in our code
import React, {useState, useEffect} from 'react';

// import all the components we are going to use
import {SafeAreaView, StyleSheet, Text, View} from 'react-native';

// import CountDown to show the timer
import CountDown from 'react-native-countdown-component';

// import moment to help you play with date and time
import moment from 'moment';

const App = () => {
  const [totalDuration, setTotalDuration] = useState(0);

  useEffect(() => {
    // Coundown timer for a given expiry date-time
    let date = 
      moment()
        .utcOffset('+05:30')
        .format('YYYY-MM-DD hh:mm:ss');
    
    // Getting the current date-time
    // You can set your own date-time
    let expirydate = '2020-12-23 04:00:45';
    
    let diffr = 
      moment
        .duration(moment(expirydate)
        .diff(moment(date)));
    // Difference of the expiry date-time
    var hours = parseInt(diffr.asHours());
    var minutes = parseInt(diffr.minutes());
    var seconds = parseInt(diffr.seconds());

    // Converting in seconds
    var d = hours * 60 * 60 + minutes * 60 + seconds;

    // Settign up the duration of countdown
    setTotalDuration(d);
  }, []);

  return (
    <SafeAreaView style={styles.container}>
      <View style={styles.container}>
        <Text style={styles.title}>
          React Native CountDown Timer | 
          react-native-countdown-component
        </Text>
        <CountDown
          until={totalDuration}
          //duration of countdown in seconds
          timetoShow={('H', 'M', 'S')}
          //formate to show
          onFinish={() => alert('finished')}
          //on Finish call
          onPress={() => alert('hello')}
          //on Press call
          size={20}
        />
      </View>
    </SafeAreaView>
  );
};

export default App;

const styles = StyleSheet.create({
  container: {
    flex: 1,
    padding: 10,
    justifyContent: 'center',
    alignItems: 'center',
  },
  title: {
    textAlign: 'center',
    fontSize: 20,
    fontWeight: 'bold',
    padding: 20,
  },
});

To Run the React Native App

Open the terminal again and jump into your project using.

cd ProjectName

1. Start Metro Bundler

First, you will need to start Metro, the JavaScript bundler that ships with React Native. To start Metro bundler run following command:

npx react-native start

Once you start Metro Bundler it will run forever on your terminal until you close it. Let Metro Bundler run in its own terminal. Open a new terminal and run the application.

2. Start React Native Application

To run the project on an Android Virtual Device or on real debugging device:

npx react-native run-android

or on the iOS Simulator by running (macOS only)

npx react-native run-ios

Output Screenshots

Output in Online Emulator

That was the React Native Count Down Timer. If you have any doubts or want to share something about the topic you can comment below or contact us here. There will be more posts coming soon. Stay tuned!

Hope you liked it. 🙂