Added addEventListeners() and addListenerToEvents() methods. Moved isElement into a first class function then added back to the returned Utils object.

app/js/common/Utils.js

@@ -1,3 +1,22 @@
+
+function isElement(el){
+  // Code based on...
+  // https://stackoverflow.com/questions/384286/javascript-isdom-how-do-you-check-if-a-javascript-object-is-a-dom-object
+  try {
+    // Using W3 DOM2 (works for FF, Opera and Chrome)
+    return el instanceof HTMLElement;
+  } catch(e) {
+    // Browsers not supporting W3 DOM2 don't have HTMLElement and
+    // an exception is thrown and we end up here. Testing some
+    // properties that all elements have (works on IE7)
+    return (typeof(el) === "object") && 
+      (el.nodeType === 1) && 
+      (typeof(el.style) === "object") &&
+      (typeof(el.ownerDocument) === "object");
+  }
+}
+
+
 const utils = {
   isInt:function(v){
     if (isNaN(v)){
@@ -7,21 +26,25 @@ const utils = {
     return (x | 0) === x;
   },
 
-  isElement:function(el){
-    // Code based on...
-    // https://stackoverflow.com/questions/384286/javascript-isdom-how-do-you-check-if-a-javascript-object-is-a-dom-object
-    try {
-      // Using W3 DOM2 (works for FF, Opera and Chrome)
-      return el instanceof HTMLElement;
-    } catch(e) {
-      // Browsers not supporting W3 DOM2 don't have HTMLElement and
-      // an exception is thrown and we end up here. Testing some
-      // properties that all elements have (works on IE7)
-      return (typeof(el) === "object") && 
-        (el.nodeType === 1) && 
-        (typeof(el.style) === "object") &&
-        (typeof(el.ownerDocument) === "object");
-      }
+  isElement:isElement,
+  addEventListeners(el, listeners){
+    if (!isElement(el))
+      throw new TypeError("Can only attach listeners to HTMLElement objects.");
+    Objects.keys(listeners).forEach((key) => {
+      el.addEventListener(key, listeners[key]);
+    });
+  },
+
+  addListenerToEvents(el, enames, listener){
+    if (!isElement(el))
+      throw new TypeError("Can only attach listeners to HTMLElement objects.");
+    if (!(enames instanceof Array))
+      throw new TypeError("Expected an array of event name strings.");
+    if (typeof(listener) !== 'function')
+      throw new TypeError("Listener expected to be a function.");
+    enames.forEach((name) => {
+      el.addEventListener(name, listener);
+    });
   },
 
   range:function(a, b, step){