Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

The BatteryManager.onlevelchange property specifies an event listener to receive levelchange events. These events occur when the battery level is updated.


navigator.battery.onlevelchange = funcRef

Where battery is a BatteryManager object, and funcRef is a function to be called when the levelchange event occurs.



<div id="level">(battery level unknown)</div>
<div id="stateBattery">(charging state unknown)</div>


navigator.getBattery().then(function(battery) {
  battery.onlevelchange = function(){
    document.querySelector('#level').textContent = battery.level;

    if(battery.charging) {
      document.querySelector('#stateBattery').textContent =
          "Charging time: " + (battery.chargingTime / 60);
    else {
      document.querySelector('#stateBattery').textContent =
          "Discharging time: " + (battery.dischargingTime / 60);


Battery Status API
# dom-batterymanager-onlevelchange

Browser compatibility

BCD tables only load in the browser

See also