housekeeping in main.js

adding some comments

restructured keylisteners

static/main.js

@@ -1,4 +1,7 @@
+
 var localModeEnabled = false;
+
+// References to howler objects 
 var howlerSounds = [];
 
 function ready(fn) {
@@ -58,43 +61,51 @@ ready(function() {
 	reset.addEventListener("click", resetSearch, false);
 	sounds_nav.addEventListener("click", resetSearch, false);
 
-	// keyboard listener for global key strokes/inputs
+	addKeyListeners();
-	document.onkeydown = function(evt) {
-    		evt = evt || window.event;
-		if (evt.keyCode == 27) {
-			// esc key
-			resetSearch();
-		} else if ((evt.keyCode == 75 || evt.keyCode == 67) && evt.ctrlKey) {
-			// ctrl+k and ctrl+c key binding
-			killAllAudio();
-		} else if (evt.keyCode == 88 && evt.ctrlKey){
-			toggleLocalMode();			
-		}	
-	};
-	
-	// TODO: make sure that only sound buttons get selected, not ALL a-tags. See d4377e0f49dc8dd5787f4466c9ab7f7e7cd37ec5#note_857
-	// keyboard listener for enter key
-	var all_a_s = document.getElementsByTagName("a"); 
-	for(i=0; i<all_a_s.length; i++) {	
-	    all_a_s[i].addEventListener('keypress', async function (e) {
-		    var key = e.keyCode;
-		    var source = e.target;
-		    // keylistener for enter or ctrl+enter (which is k10 on chrome)
-		    if (key === 13 || (key === 10 && e.ctrlKey)) {
-			if(e.ctrlKey){
-				killAllAudio();
-				await sleep(100);
-			}
-			source.classList.add("sound-pressed");
-		    	source.onclick(); 
-			await sleep(300);
-			source.classList.remove("sound-pressed"); 
-		    }
-		});
-	}
-
 });
 
+/*
+* Adds all necessary KeyListeners to document
+*/
+function addKeyListeners() {
+        // keyboard listener for global key strokes/inputs
+        document.onkeydown = function(evt) {
+                evt = evt || window.event;
+                if (evt.keyCode == 27) {
+                        // esc key
+                        resetSearch();
+                } else if ((evt.keyCode == 75 || evt.keyCode == 67) && evt.ctrlKey) {
+                        // ctrl+k and ctrl+c key binding
+                        killAllAudio();
+                } else if (evt.keyCode == 88 && evt.ctrlKey){
+                        // ctrl+x key binding
+                        toggleLocalMode();
+                }
+        };
+
+
+        // TODO: make sure that only sound buttons get selected, not ALL a-tags. See d4377e0f49dc8dd5787f4466c9ab7f7e7cd37ec5#note_857
+        // keyboard listener for playing sounds using enter key
+        var all_a_s = document.getElementsByTagName("a");
+        for(i=0; i<all_a_s.length; i++) {
+            all_a_s[i].addEventListener('keypress', async function (e) {
+                    var key = e.keyCode;
+                    var source = e.target;
+                    // keylistener for enter or ctrl+enter (which is k10 on chrome)
+                    if (key === 13 || (key === 10 && e.ctrlKey)) {
+                        if(e.ctrlKey){
+                                killAllAudio();
+                                await sleep(100);
+                        }
+                        source.classList.add("sound-pressed");
+                        source.onclick();
+                        await sleep(300);
+                        source.classList.remove("sound-pressed");
+                    }
+                });
+        }
+}
+
 
 function resetSearch() {
 	var searchfield = document.querySelector("#search");
@@ -108,6 +119,9 @@ function resetSearch() {
 	searchfield.focus();
 }
 
+/*
+* Reads the stream url from input with id #streaming-url and forwards it to the server using AJAX.
+*/
 function playStream(){
 	var streamUrl = document.querySelector("#streaming-url").value;
 	ajaxRequest("/?video="+encodeURI(streamUrl));	
@@ -128,11 +142,15 @@ function ajaxRequest(url){
         ajaxRequest.open("GET", url, true);
         ajaxRequest.send(null);
     }catch (e){
-        alert("Your browser broke!");
+        alert("Unfortunately we were unable to handle your request. Please try again later and contact the server administrator if the problem persists.");
         return false;
     }
 }
 
+/*
+* Switches between local and remote playback mode.
+* Additionally changes the button text and its color so that the user has a visible feedback.
+/*
 function toggleLocalMode(){
 	toggleButton = document.getElementById("local-mode-button").children[0];
 	if(localModeEnabled){
@@ -148,6 +166,9 @@ function toggleLocalMode(){
 	}	
 }
 
+/*
+* Either plays the given sound file locally by using howler.js or forwards the request to the remote server using AJAX.
+*/
 function playSound(filename){
 	if(localModeEnabled){
 		// play local audio using howler.js
@@ -167,6 +188,9 @@ function killAllHowlerAudio(){
 	}	
 }
 
+/*
+* Kills all local or remote audio, depending on localModeEnabled
+*/
 function killAllAudio(){
 	if (localModeEnabled) {
         	killAllHowlerAudio();