Use proper prototypal inheritance and less dynamic new

js/id/connection.js

@@ -77,15 +77,8 @@ iD.Connection = function() {
             delete o.lat;
         }
         o.id = iD.Entity.id.fromOSM(o.type, o.id);
-        switch (o.type) {
-            case 'node':
-                o._poi = !refNodes[o.id];
-                return iD.Node(o);
-            case 'way':
-                return iD.Way(o);
-            case 'relation':
-                return iD.Relation(o);
-        }
+        if (o.type === 'node')  o._poi = !refNodes[o.id];
+        return new iD.Entity[o.type](o);
     }
 
     function parse(dom) {

js/id/graph/entity.js

@@ -109,16 +109,3 @@ iD.Entity.prototype = {
         return n.length === 0 ? 'unknown' : n.join('; ');
     }
 };
-
-iD.Entity.extend = function(properties) {
-    var Subclass = function() {
-        if (this instanceof Subclass) return;
-        return (new Subclass()).initialize(arguments);
-    };
-
-    Subclass.prototype = new iD.Entity();
-    _.extend(Subclass.prototype, properties);
-    iD.Entity[properties.type] = Subclass;
-
-    return Subclass;
-};

js/id/graph/node.js

@@ -1,4 +1,14 @@
-iD.Node = iD.Entity.extend({
+iD.Node = iD.Entity.node = function iD_Node() {
+    if (!(this instanceof iD_Node)) {
+        return (new iD_Node()).initialize(arguments);
+    } else if (arguments.length) {
+        this.initialize(arguments);
+    }
+};
+
+iD.Node.prototype = Object.create(iD.Entity.prototype);
+
+_.extend(iD.Node.prototype, {
     type: "node",
 
     extent: function() {

js/id/graph/relation.js

@@ -1,4 +1,14 @@
-iD.Relation = iD.Entity.extend({
+iD.Relation = iD.Entity.relation = function iD_Relation() {
+    if (!(this instanceof iD_Relation)) {
+        return (new iD_Relation()).initialize(arguments);
+    } else if (arguments.length) {
+        this.initialize(arguments);
+    }
+};
+
+iD.Relation.prototype = Object.create(iD.Entity.prototype);
+
+_.extend(iD.Relation.prototype, {
     type: "relation",
     members: [],
 

js/id/graph/way.js

@@ -1,4 +1,14 @@
-iD.Way = iD.Entity.extend({
+iD.Way = iD.Entity.way = function iD_Way() {
+    if (!(this instanceof iD_Way)) {
+        return (new iD_Way()).initialize(arguments);
+    } else if (arguments.length) {
+        this.initialize(arguments);
+    }
+};
+
+iD.Way.prototype = Object.create(iD.Entity.prototype);
+
+_.extend(iD.Way.prototype, {
     type: "way",
     nodes: [],