Battery API All In One
navigator.getBattery()
/*
Promise {<pending>}__proto__: Promise[[PromiseState]]: "fulfilled"[[PromiseResult]]: BatteryManagercharging: truechargingTime: 0dischargingTime: Infinitylevel: 1onchargingchange: nullonchargingtimechange: nullondischargingtimechange: nullonlevelchange: null__proto__: BatteryManager
*/
W3C
Battery Status API
W3C Candidate Recommendation 07 July 2016
Battery Status API
W3C Editor's Draft 25 September 2019