Updating the readme and using the empty function

Author: thoov

README.md

@@ -23,21 +23,50 @@ buffer.get('firstName'); // => 'stefan'
 buffer.set('firstName', 'Kris');
 
 buffer.get('firstName'); // => 'Kris'
-buffer.get('firstName.content'); // => 'stefan'
+buffer.get('content.firstName'); // => 'stefan'
 
 buffer.applyBufferedChanges();
 
 buffer.get('firstName'); // => 'Kris'
-buffer.get('firstName.content'); // => 'Kris'
+buffer.get('content.firstName'); // => 'Kris'
 
 buffer.set('firstName', 'Luke');
 buffer.get('firstName'); // => 'Luke'
-buffer.get('firstName.content'); // => 'Kris'
+buffer.get('content.firstName'); // => 'Kris'
 
 buffer.discardBufferedChanges();
 
 buffer.get('firstName'); // => 'Kris'
-buffer.get('firstName.content'); // => 'Kris'
+buffer.get('content.firstName'); // => 'Kris'
+
+// Below demonstrates that applyBufferedChanges and discardBufferedChanges
+// can take an optional array of keys.
+
+buffer.set('email', 'example@example.com');
+buffer.get('email'); // => 'example@example.com'
+buffer.get('content.email'); // => undefined
+
+buffer.set('address', '123 paradise road');
+buffer.get('address'); // => '123 paradise road'
+buffer.get('content.address'); // => undefined
+
+buffer.applyBufferedChanges(['email']); // Only apply the email from the buffer
+
+buffer.get('email'); // => 'example@example.com'
+buffer.get('address'); // => '123 paradise road'
+buffer.get('content.email'); // => 'example@example.com'
+buffer.get('content.address'); // => undefined
+
+buffer.setProperties({
+  'email', 'sample@sample.com',
+  'address', '1717 rose street'
+});
+
+buffer.discardBufferedChanges(['address']); // Discard only the address property from the buffer
+
+buffer.get('email'); // => example@example.com
+buffer.get('address'); // => 1717 rose street
+
 ```
 
 Or you can grab the mixin directly

addon/mixin.js

@@ -22,11 +22,9 @@ export default Ember.Mixin.create({
   },
 
   initializeBuffer: function(onlyTheseKeys) {
-    if(isArray(onlyTheseKeys) && onlyTheseKeys.length > 0) {
-      keys(this.buffer).forEach(function(key) {
-        if(onlyTheseKeys.contains(key)) {
-          delete this.buffer[key];
-        }
+    if(isArray(onlyTheseKeys) && !empty(onlyTheseKeys)) {
+      onlyTheseKeys.forEach(function(key) {
+        delete this.buffer[key];
       }, this);
     }
     else {
@@ -90,7 +88,7 @@ export default Ember.Mixin.create({
 
     this.initializeBuffer(onlyTheseKeys);
 
-    if (keys(this.buffer).length === 0) {
+    if (empty(this.buffer)) {
       this.set('hasBufferedChanges', false);
     }
   },
@@ -109,7 +107,7 @@ export default Ember.Mixin.create({
       this.propertyDidChange(key);
     }, this);
 
-    if (keys(this.buffer).length === 0) {
+    if (empty(this.buffer)) {
       this.set('hasBufferedChanges', false);
     }
   }