Let’s talk about how the front-end obtains battery information

Positive energy today: When there are more and more strange demands, it proves that your vision is also becoming broader.

Product Manager: I would like to add a request. If the user’s computer equipment is about to run out of power, I want to warmly tell him that he should plug it in.

Front-end Siege Lion:. . . Wouldn't his computer remind him?

Product Manager: Do you want to do it?

Front-end Siege Lion: Do it!

Preface

With the increasing development of technology, web front-end technology is far more powerful than we imagined. The browser allows websites to obtain battery status information of the user's device, such as battery percentage, remaining power, charging status, and more. We can use this information to adjust our app behavior based on the battery level of the user's device. In this article, we will explore how to get battery information in the front end, using the Battery Status API.

Usage of Battery Status API

Battery Status API is a Web API that allows web applications to access battery status information of user devices. Using this API, we can read the device's battery information directly from the web browser without installing any application.

The main steps to obtain device battery information are as follows:

// 请求电池信息
navigator.getBattery().then(function (battery) {
  // 后续代码
})

will return a Promise object, which will be resolved into a BatteryManager object, which we can use to read the battery properties of the device.

navigator.getBattery().then(function (battery) {
  // 获取设备电量剩余百分比
  var level = battery.level //最大值为1,对应电量100%
  console.log('Level: ' + level * 100 + '%')

  // 获取设备充电状态
  var charging = battery.charging
  console.log('充电状态: ' + charging)

  // 获取设备完全充电需要的时间
  var chargingTime = battery.chargingTime
  console.log('完全充电需要的时间: ' + chargingTime)

  // 获取设备完全放电需要的时间
  var dischargingTime = battery.dischargingTime
  console.log('完全放电需要的时间: ' + dischargingTime)
})

Listen to battery status changes

In order to better reflect the battery status of the user device, we can add events to the front end to monitor battery status changes. For example, an event is triggered when the device's battery level changes. Let me list some common events for you:

navigator.getBattery().then(function (battery) {
  // 添加事件，当设备电量改变时触发
  battery.addEventListener('levelchange', function () {
    console.log('电量改变: ' + battery.level)
  })

  // 添加事件，当设备充电状态改变时触发
  battery.addEventListener('chargingchange', function () {
    console.log('充电状态改变: ' + battery.charging)
  })

  // 添加事件，当设备完全充电需要时间改变时触发
  battery.addEventListener('chargingtimechange', function () {
    console.log('完全充电需要时间: ' + battery.chargingTime)
  })

  // 添加事件，当设备完全放电需要时间改变时触发
  battery.addEventListener('dischargingtimechange', function () {
    console.log('完全放电需要时间: ' + battery.dischargingTime)
  })
})

Compatibility

In terms of compatibility, the Battery Status API is not applicable to all devices and operating systems. Developers need to handle compatibility. To ensure that our application can run on all devices. The following is the compatibility view corresponding to this API:

Obtaining device battery information through the Battery Status API is a very powerful method that can optimize applications based on device battery status. the behavior of. It's important to note that this API doesn't work on all devices and operating systems, and some device manufacturers may not allow battery information to be shared.

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