Return undefined for stuff instead of null.

src/model_class_methods.js

@@ -36,8 +36,6 @@ Model.ClassMethods = {
       model = all[i]
       if (func.call(model, i)) return model
     }
-
-    return null
   },
 
   each: function(func) {
@@ -53,11 +51,11 @@ Model.ClassMethods = {
   find: function(id) {
     return this.detect(function() {
       return this.id() == id;
-    }) || null;
+    })
   },
 
   first: function() {
-    return this.all()[0] || null;
+    return this.all()[0]
   },
 
   load: function(callback) {
@@ -78,7 +76,7 @@ Model.ClassMethods = {
 
   last: function() {
     var all = this.all();
-    return all[all.length - 1] || null;
+    return all[all.length - 1]
   },
 
   pluck: function(attribute) {

src/model_instance_methods.js

@@ -78,7 +78,7 @@ Model.InstanceMethods = {
   },
 
   id: function() {
-    return this.attributes.id || null;
+    return this.attributes.id
   },
 
   merge: function(attributes) {
@@ -87,7 +87,7 @@ Model.InstanceMethods = {
   },
 
   newRecord: function() {
-    return this.id() === null;
+    return this.id() === undefined
   },
 
   reset: function() {

src/model_rest.js

@@ -79,7 +79,7 @@ Model.REST = function(resource, methods) {
     xhr: function(method, url, model, callback) {
       var self = this;
       var data = jQuery.inArray(method, ["DELETE", "GET"]) > -1 ?
-        null : this.params(model);
+        undefined : this.params(model);
 
       return jQuery.ajax({
         type: method,
@@ -88,7 +88,7 @@ Model.REST = function(resource, methods) {
         dataType: "json",
         data: data,
         dataFilter: function(data, type) {
-          return /\S/.test(data) ? data : null;
+          return /\S/.test(data) ? data : undefined;
         },
         complete: function(xhr, textStatus) {
           self.xhrComplete(xhr, textStatus, model, callback)
@@ -140,7 +140,7 @@ Model.REST.parseResponseData = function(xhr) {
   try {
     return /\S/.test(xhr.responseText) ?
       jQuery.parseJSON(xhr.responseText) :
-      null;
+      undefined;
   } catch(e) {
     Model.Log(e);
   }

test/tests/model_class_methods.js

@@ -9,9 +9,9 @@ test("all, count, find, first, add, remove", function() {
 
   same(Post.all(), []);
   equals(Post.count(), 0);
-  ok(Post.find(1) === null);
-  ok(Post.first() === null);
-  ok(Post.last() === null);
+  ok(Post.find(1) === undefined);
+  ok(Post.first() === undefined);
+  ok(Post.last() === undefined);
 
   Post.add(post1, post2).add(post3);
 
@@ -20,19 +20,19 @@ test("all, count, find, first, add, remove", function() {
   equals(Post.find(1), post1);
   equals(Post.find(2), post2);
   equals(Post.find(3), post3);
-  equals(Post.find(4), null);
+  equals(Post.find(4), undefined);
   equals(Post.first(), post1);
 
   ok(Post.remove(post2));
 
   same(Post.pluck("id"), [1, 3]);
   equals(Post.count(), 2);
   equals(Post.find(1), post1);
-  ok(Post.find(2) === null);
+  ok(Post.find(2) === undefined);
   equals(Post.find(3), post3);
-  ok(Post.find(4) === null);
+  ok(Post.find(4) === undefined);
 
-  ok(!Post.remove(null));
+  ok(!Post.remove(undefined));
 });
 
 test("maintaining a collection of unique models by object, id and uid", function() {
@@ -88,7 +88,7 @@ test("detect, select, first, last, count (with chaining)", function() {
   ok(Post.detect(function(i) {
     indexes.push(i);
     return this.attr("title") == "Baz";
-  }) === null);
+  }) === undefined);
 
   same(indexes, [0, 1, 2], "should yield index correctly");
   indexes = [];

test/tests/model_rest.js

@@ -95,7 +95,7 @@ test("destroy with named params in resource path", function() {
 
   equals(request.type, "DELETE");
   equals(request.url, "/root/3/nested/2/posts/1");
-  same(request.data, null);
+  same(request.data, undefined);
 });
 
 test("create", function() {
@@ -280,7 +280,7 @@ test("destroy", function() {
 
   equals(request.type, "DELETE");
   equals(request.url, "/posts/1");
-  same(request.data, null);
+  same(request.data, undefined);
 });
 
 test("destroy failure", function() {