create timer with react native using es6

I'm not really sure how that would work even without any other UI interactions. componentDidUpdate is called every time the component is re-rendered, something that happens when the internal state or passed down props have changed. Not something you can count on to happen exactly every second.

How about moving the getTimerCountDown to your componentDidMount method (which is only called once), and then using setInterval instead of setTimeout to make sure the counter is decremented continuously?

Kinda late, but you can try out this component I made for dealing with timers and es6 components in react-native:

https://github.com/fractaltech/react-native-timer

Idea is simple, maintaining and clearing timer variables on the components is a pain, so simply, maintain them in a separate module. Example:

// not using ES6 modules as babel has broken interop with commonjs for defaults 
const timer = require('react-native-timer');

// timers maintained in the Map timer.timeouts 
timer.setTimeout(name, fn, interval);
timer.clearTimeout(name);

// timers maintained in the Map timer.intervals 
timer.setInterval(name, fn, interval);
timer.clearInterval(name);

// timers maintained in the Map timer.immediates 
timer.setImmediate(name, fn);
timer.clearImmediate(name);

// timers maintained in the Map timer.animationFrames 
timer.requestAnimationFrame(name, fn);
timer.cancelAnimationFrame(name);