declarations.d.ts

interface Connection extends EventTarget {
  readonly downlink: number;
  readonly downlinkMax: number;
  readonly effectiveType: 'slow-2g' | '2g' | '3g' | '4g';
  readonly rtt: number;
  readonly saveData: boolean;
  readonly type:
    | 'bluetooth'
    | 'cellular'
    | 'ethernet'
    | 'mixed'
    | 'none'
    | 'other'
    | 'unknown'
    | 'wifi'
    | 'wimax';
  onChange: (event: Event) => void;
}

interface BatteryManager extends EventTarget {
  charging: boolean;
  chargingTime: number;
  dischargingTime: number;
  level: number;
}

interface Navigator {
  readonly connection: Connection;
  readonly mozConnection: Connection;
  readonly webkitConnection: Connection;
  readonly getBattery: () => Promise<BatteryManager>;
}