Added Evented#addListener as #on alias

Consistent with Node.js' event API

src/event/Evented.js

@@ -235,6 +235,19 @@ module.exports = Trait( 'Evented',
     },
 
 
+    /**
+     * Alias for #on
+     *
+     * @see {#on}
+     */
+    addListener( ev, listener )
+    {
+        // we proxy to `on` (instead of the reverse) because `on` is
+        // traditionally more often used, so we want to save overhead there
+        return this.on( ev, listener );
+    },
+
+
     /**
      * Removes a previously hooked listener in constant time, preventing it
      * from being invoked on future emits of event EV

test/event/EventedTest.js

@@ -141,48 +141,54 @@ describe( 'event.Evented', () =>
     } );
 
 
-    describe( '#on', () =>
+    /**
+     * `addListener` is an alias for `on` (consistent with Node.js' API)
+     */
+    [ 'on', 'addListener' ].forEach( on =>
     {
-        it( 'does not allow hooking undeclared events', () =>
+        describe( ( '#' + on ), () =>
         {
-            var badevent = 'bazbar';
+            it( 'does not allow hooking undeclared events', () =>
+            {
+                var badevent = 'bazbar';
 
-            expect( () => stub.on( badevent, ()=>{} ) )
+                expect( () => stub[ on ]( badevent, ()=>{} ) )
-                .to.throw( Error, badevent );
+                    .to.throw( Error, badevent );
-        } );
+            } );
 
 
-        it( 'allows hooking declared events', () =>
+            it( 'allows hooking declared events', () =>
-        {
+            {
-            var name = 'testev';
+                var name = 'testev';
-            stub.evDefineEvents( [ name ] )
+                stub.evDefineEvents( [ name ] )
-                .on( name, ()=>{} );
+                    [ on ]( name, ()=>{} );
-        } );
+            } );
 
 
-        it( 'returns self', () =>
+            it( 'returns self', () =>
-        {
+            {
-            var name = 'testev';
+                var name = 'testev';
 
-            var ret = stub.evDefineEvents( [ name ] )
+                var ret = stub.evDefineEvents( [ name ] )
-                .on( name, ()=>{} );
+                    [ on ]( name, ()=>{} );
 
-            expect( ret ).to.equal( stub );
+                expect( ret ).to.equal( stub );
-        } );
+            } );
 
 
-        it( 'requires that listener is a function', () =>
+            it( 'requires that listener is a function', () =>
-        {
+            {
-            var ev = 'foo';
+                var ev = 'foo';
-            stub.evDefineEvents( [ ev ] );
+                stub.evDefineEvents( [ ev ] );
 
-            // OK
+                // OK
-            expect( () => stub.on( ev, ()=>{} ) )
+                expect( () => stub[ on ]( ev, ()=>{} ) )
-                .to.not.throw( TypeError );
+                    .to.not.throw( TypeError );
 
-            // bad
+                // bad
-            expect( () => stub.on( ev, "kittens" ) )
+                expect( () => stub[ on ]( ev, "kittens" ) )
-                .to.throw( TypeError );
+                    .to.throw( TypeError );
+            } );
         } );
     } );