webmusic.js: use arrow functions everywhere

webmusic.js

@@ -70,39 +70,39 @@ const initState = () => {
 	document.getElementById("repeatButton").addEventListener("click", toggleRepeat)
 	document.getElementById("continuousButton").addEventListener("click", toggleContinue)
 
-	audioPlayer.addEventListener("canplay", function () {
+	audioPlayer.addEventListener("canplay", () => {
 		audioPlayer.play();
 	});
 
-	audioPlayer.addEventListener("play", function () {
+	audioPlayer.addEventListener("play", () => {
 		setPlayerState("playing");
 	});
 
-	audioPlayer.addEventListener("pause", function () {
+	audioPlayer.addEventListener("pause", () => {
 		setPlayerState("paused");
 	});
 
-	audioPlayer.addEventListener("error", function () {
+	audioPlayer.addEventListener("error", () => {
 		setPlayerState("error loading track");
 	});
 
-	audioPlayer.addEventListener("ended", function () {
+	audioPlayer.addEventListener("ended", () => {
 		setPlayerState("idle");
 		nextTrack();
 	});
 
-	audioPlayer.addEventListener("timeupdate", function () {
+	audioPlayer.addEventListener("timeupdate", () => {
 		updatePlayerState();
 	});
 
-	dirElements.forEach(function(element){
+	dirElements.forEach((element) => {
 		element.id = id++;
 	});
 
-	fileElements.forEach(function(element){
+	fileElements.forEach((element) => {
 		element.id = id++;
 
-		element.addEventListener("click", function(event) {
+		element.addEventListener("click", (event) => {
 			event.preventDefault();
 			event.stopPropagation();
 			playSong(event.target.id);