Battery Status API

HTML

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Battery Status</title>
</head>
<body>
    <header>
        <h1>Battery Status</h1>
    </header>
    <article>
        <textarea id="result"></textarea>           
    </article>
</body>
</html>

CSS

body {
    font-family: "Verdana";
    font-size: 9pt;
}

header {
    padding: 15px;
    box-shadow: 0px 1px 2px rgba(0,0,0,0.4);
    background-color: rgb(27, 161, 226);
    color: #fff;
}

    header h1 {
        font-size: 14pt;
    }


article {
    width: 80%;
    margin: auto;
    margin-top: 20px;
}

textarea {
    font-family: "Consolas";
    font-size: 9pt;
    width: 400px;
    height: 300px;
}

JavaScript

function log(msg){
    var output = document.getElementById("result");
    output.value += msg;
}

window.onload = function() {

    var battery = navigator.getBattery().then(function(battery) {
    
   		if (battery) {

        var level = battery.level * 100;
        var dischargingTime = Math.round(battery.dischargingTime / 60);
        var chargingTime = Math.round(battery.chargingTime / 60);
        var IsCharging = battery.charging;
        
        var info = "Battery Level: " + level + "%" +
                  "\nDischarging in " + dischargingTime + " minutes" +
                  "\nCharging in " + chargingTime + " minutes" +
                  "\nIs It Charging?: " + IsCharging;
     
        log(info);
        
        //Handlers
        battery.addEventListener("levelchange", function(){
            level = battery.level * 100;
            log("\nBattery level is changed to: " + level + "%");
        });
        
        battery.addEventListener("chargingchange", function(){
            if(battery.charging)
                log("\nCharging");
            else
                log("\nNot charging");
        });
        
        battery.addEventListener("chargingchange",function(){
            chargingTime = Math.round(battery.chargingTime / 60);
            log("\nCharging time is changed to: " + chargingTime  + " minutes");
        });
        
        battery.addEventListener("dischargingtimechange",function(){
            dischargingTime = Math.round(battery.dischargingTime / 60);
            log("\nDischarging time is changed to: " + dischargingTime + " minutes");
        });

    	}
      else {
          log("Battery Status API is not available");
      }
		});
};