React Native Timer Countdown

A highly customizable countdown component for React Native (iOS and Android).

Install

npm install --save react-native-timer-countdown

or

yarn add react-native-timer-countdown

Usage

import React from "react";
import { StyleSheet, View } from "react-native";
import TimerCountdown from "react-native-timer-countdown";

const App = () => (
  <View style={styles.container}>
    <TimerCountdown
      initialSecondsRemaining={1000 * 60}
      onTick={(secondsRemaining) => console.log("tick", secondsRemaining)}
      onComplete={() => console.log("complete")}
      formatSecondsRemaining={(milliseconds) => {
        const remainingSec = Math.round(milliseconds / 1000);
        const seconds = parseInt((remainingSec % 60).toString(), 10);
        const minutes = parseInt(((remainingSec / 60) % 60).toString(), 10);
        const hours = parseInt((remainingSec / 3600).toString(), 10);
        const s = seconds < 10 ? '0' + seconds : seconds;
        const m = minutes < 10 ? '0' + minutes : minutes;
        let h = hours < 10 ? '0' + hours : hours;
        h = h === '00' ? '' : h + ':';
        return h + m + ':' + s;
      }}
      allowFontScaling={true}
      style={{ fontSize: 20 }}
    />
  </View>
);

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#fff",
    alignItems: "center",
    justifyContent: "center"
  }
});

export default App;

Props

Name	Description	Type	Required	Default Value
initialSecondsRemaining	The time remaining for the countdown (in ms)	number	✓
formatSecondsRemaining	A function that formats the secondsRemaining	func
onTick	A function to call each tick. It returns the remaining seconds.	func
onComplete	A function to call when the countdown completes	func
allowFontScaling	to allow font scaling	bool		false
style	The custom styling which will be applied to the Text component	style

FAQ

Why does this timer restart whenever I click any button?

What's happening

buttons clicked -> state changes -> react rerenders -> timer restarts

How to not to restart the timer component

Provided the state changes only occur in component B, A component will not rerender. As a result, no more unintended timer restarts.

import React, { Component } from "react";
import { StyleSheet, Button, View } from "react-native";
import TimerCountdown from "react-native-timer-countdown";

const A = () => (
  <View style={styles.container}>
    <B />
    <TimerCountdown initialSecondsRemaining={1000 * 60} />
  </View>
);
export default A;

class B extends Component {
  state = { isPressed: false };
  render() {
    return (
      <View styles={{ flex: 1 }}>
        <Button
          title={`${this.state.isPressed ? "Button Pressed" : "Button"}`}
          onPress={() => {
            this.setState({ isPressed: true });
          }}
        />
      </View>
    );
  }
}


const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#fff",
    alignItems: "center",
    justifyContent: "center"
  }
});

Author

Noel Yoo

License

MIT