HTML

<div class="zib-widget">

        <div class="text-center">
            <h3>电池</h3>

            <div class="batteryShape">

                <div class="level">

                    <div class="percentage" style="width: 100%;">

                    </div>
                </div>
            </div>

            <div class="percent">100%</div>

            <p class="batteryTime">正在充电</p>

        </div>
    </div>

CSS

/*电池电量*/
.batteryShape{
    position: relative;
    width: 140px;
    height: 65px;
    margin: auto;
    border: 3px solid #333;
    border-radius: 10px;
}
.batteryShape::before{
    content: '';
    position: absolute;
    top: 50%;
    right: -12px;
    margin-left: 2px;
    transform: translateY(-50%);
    width: 7px;
    height: 16px;
    background: #333;
    border-top-right-radius: 4px;
    border-bottom-right-radius: 4px;
}
.batteryShape::after{
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 50%;
    background: rgba(255,255,255,.1);
}
.level{
    position: absolute;
    top: 4px;
    right: 4px;
    bottom: 4px;
    left: 4px;
    border-radius: 4px;
    overflow: hidden;
}
.percentage{
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 50%;
    background: linear-gradient(90deg,#9c27b0,#fd2c72);
}
.batteryTime{
    font-size: 0.6em;
    color: #333333;
    letter-spacing: -0.6px;
}

JavaScript

// 充电状态
var pt = document.querySelector('.percentage');
var p = document.querySelector('.percent');
//获取电池状态
navigator.getBattery().then(function(battery) {

    //初始化电量
    pt.style.width = battery.level * 100 + "%";
    p.innerHTML = battery.level * 100 + "%"
    //监听电量变化
    battery.addEventListener("levelchange", function (e) {
        console.log("电量水平变化: ", battery.level);
        pt.style.width = battery.level * 100 + "%";
        p.innerHTML = battery.level * 100 + "%"
    }, false);


    //初始化电池状态变化
    var charging = battery.charging ? "yes" : "no";
    if (charging === "yes"){
        document.querySelector('.batteryTime').innerHTML = '正在充电';
    }else {
        document.querySelector('.batteryTime').innerHTML = '未在充电';
    }
    //监听电池充电状态变化
       battery.addEventListener("chargingchange", function (e) {
        console.warn("电池充电状态变化: ", battery.charging);
        var cd = battery.charging?'yes':'no';
       if (cd == 'yes'){
               document.getElementsByClassName('batteryTime')[0].innerHTML = '正在充电';
        }else {
            document.getElementsByClassName('batteryTime')[0].innerHTML = '未在充电';
        }
    }, false);
});