Merge pull request #7 from nickdesaulniers/objListener

allow obj listeners with handleEvent methods Fixes #6
mysticatea · Dec 17, 2015 · a08a57f · a08a57f
2 parents 58e9619 + 6847d27
commit a08a57f
Show file tree

Hide file tree

Showing 2 changed files with 51 additions and 5 deletions.
diff --git a/lib/event-target.js b/lib/event-target.js
@@ -94,6 +94,11 @@ var EventTarget = module.exports = function EventTarget() {
     }
 };
 
+function hasHandleEventMethod(obj) {
+    return typeof obj === "object" && "handleEvent" in obj && typeof
+      obj.handleEvent === "function";
+}
+
 EventTarget.prototype = Object.create(
     (HAS_EVENTTARGET_INTERFACE ? window.EventTarget : Object).prototype,
     {
@@ -105,11 +110,12 @@ EventTarget.prototype = Object.create(
 
         addEventListener: {
             value: function addEventListener(type, listener, capture) {
-                if (listener == null) {
+                if (!listener) {
                     return false;
                 }
-                if (typeof listener !== "function") {
-                    throw new TypeError("listener should be a function.");
+                var isObjListener = hasHandleEventMethod(listener);
+                if (typeof listener !== "function" && !isObjListener) {
+                    throw new TypeError("listener should be a function or have a handleEvent method.");
                 }
 
                 var kind = (capture ? CAPTURE : BUBBLE);
@@ -180,7 +186,14 @@ EventTarget.prototype = Object.create(
                 // This doesn't process capturing phase and bubbling phase.
                 // This isn't participating in a tree.
                 while (node != null) {
-                    node.listener.call(this, wrapped);
+                    var isObjListener = hasHandleEventMethod(node.listener);
+                    if (isObjListener) {
+                        node.listener.handleEvent.bind(node.listener).call(this, wrapped);
+                    }
+                    else {
+                        node.listener.call(this, wrapped);
+                    }
+
                     if (wrapped[STOP_IMMEDIATE_PROPAGATION_FLAG]) {
                         break;
                     }

diff --git a/test/index.js b/test/index.js
@@ -264,12 +264,45 @@ describe("EventTarget:", function() {
         target.removeEventListener("test");
     });
 
-    it("should throw a TypeError if the listener is not a function", function() {
+    it("should throw a TypeError if the listener is not a function or object with a handleEvent method", function() {
         assert.throws(
             function() { target.addEventListener("test", "listener"); },
             TypeError
         );
     });
+
+    it("should allow a listener to be an object with a handleEvent method and have this set correctly", function() {
+        var listener = {
+            __proto__: {
+                handleEvent: function() {
+                    this.complete();
+                },
+                complete: function() {
+                    assert(true);
+                }
+            }
+        };
+        var event = createEvent("test");
+        target.addEventListener("test", listener);
+        target.dispatchEvent(event);
+    });
+
+    it("should not call removed object listeners.", function() {
+        var listener = {
+            __proto__: {
+                handleEvent: function() {
+                    this.complete();
+                },
+                complete: function() {
+                    assert(false);
+                }
+            }
+        };
+        var event = createEvent("test");
+        target.addEventListener("test", listener);
+        target.removeEventListener("test", listener);
+        target.dispatchEvent(event);
+    });
 });
 
 describe("EventTarget with attribute listeners:", function() {