Battery Status API 也就是所謂的 Battery API，將提供系統電池充電容量的資訊，並在電池容量變化時送出事件，以通知使用者。此 API 可調整 Apps 的資源耗用量，在電力偏低時縮減耗電量；或可在電力耗盡之前儲存檔案，避免資料遺失。
Battery Status API 是以 window.navigator.battery 屬性 (為 BatteryManager 物件) 而擴充了 window.navigator，並新增數項可讓使用者接收的新事件，以隨時監控電池狀態。
範例
在此範例中，我們將分別監聽 chargingchange 與 levelchange 事件，而看到充電狀態 (不論是否插電進行充電) 與電池容量的變化。
var battery = navigator.battery || navigator.mozBattery || navigator.webkitBattery;
function updateBatteryStatus() {
console.log("Battery status: " + battery.level * 100 + " %");
if (battery.charging) {
console.log("Battery is charging");
}
}
battery.addEventListener("chargingchange", updateBatteryStatus);
battery.addEventListener("levelchange", updateBatteryStatus);
updateBatteryStatus();
另可參閱規格所提供之範例。
規格
| Specification | Status | Comment |
|---|---|---|
| Battery Status API | Candidate Recommendation | Initial specification. |
瀏覽器相容性
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | Not supported Chrome on Android: crbug.com/135863 Chrome OS: crbug.com/122593 |
10 (10) moz [1] 16 (16) (without prefix) [2] |
Not supported | Not supported | Not supported |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | ? | Not supported | 10.0 (10) moz [1] 16.0 (16) (without prefix) [2] |
Not supported | Not supported | Not supported |
Gecko notes
[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.
[2] 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 OS 1.0.1).