BatteryManager.level

Indicates the current battery charge level as a value between 0.0 and 1.0.

Syntax

var level = battery.level

On return, level is a number representing the system's battery charge level scaled to a value between 0.0 and 1.0. A value of 0 means the battery, which is a BatteryManager object, is empty and the system is about to be suspended. A value of 1.0 means the battery is full. A value of 1.0 is also returned if the implementation isn't able to determine the battery charge level or if the system is not battery-powered.

Example

HTML Content

<div id="level">(battery level unknown)</div><code class="language-html">
</code>

JavaScript Content

navigator.getBattery().then(function(battery) {
       
    var level = battery.level;

    document.querySelector('#level').textContent = level;
});

Specifications

Browser compatibility

[1] Disabled by default in Firefox 10.0, but can be enabled setting the preference dom.battery.enabled to true. Starting with Firefox 11.0, mozBattery is enabled by default. The Battery API is currently supported on Android, Windows, and Linux with UPower installed. Support for MacOS is available starting with Gecko 18.0 (Firefox 18.0 / Thunderbird 18.0 / SeaMonkey 2.15). Firefox also provide support for the deprecated navigator.battery.

[2] Values for BatteryManager.chargingTime and BatteryManager.dischargingTime are always equal to Infinity.

See also

• BatteryManager
• Navigator.getBattery