JS Battery Monitor SRC V3

<script>
var u = new SpeechSynthesisUtterance();
navigator.getBattery().then(function(battery) {
battery.onlevelchange = function() {
u.text = Number(battery.level);
u.rate = Number(u.rate);
u.lang='en';
speechSynthesis.speak(u);
if(this.level==1.0){
alert('Battery Is Fully Charged!!');
u.text = ('Battery Is Fully Charged!!');
u.rate = Number(u.rate);
u.lang='en';
speechSynthesis.speak(u);
}
if(this.level==0.1){
alert('Battery Is Almost Dead!!');
u.text = ('Battery Is Almost Dead!!');
u.rate = Number(u.rate);
u.lang='en';
speechSynthesis.speak(u);
}
}
});
</script>