Battery status API

battery.js

if ('getBattery' in navigator) {
  navigator.getBattery().then(battery => {
    console.log('Initial', battery);
    battery.onchargingchange = onchange;
    battery.onchargingtimechange = onchange;
    battery.ondischargingtimechange = onchange;
    battery.onlevelchange = onchange;
    
    function onchange (event) {
      console.log('On change, type: %s', event.type, battery);
    }
  });
}