From 0d6b589e3674e0dccd013aa4790651fad81a6e78 Mon Sep 17 00:00:00 2001
From: samreid <reids@colorado.edu>
Date: Wed, 6 Jul 2016 16:16:39 -0600
Subject: [PATCH] Simplified _.extend call and clarified assert messages, see
 #243

---
 js/buttons/StepBackwardButton.js | 4 ++--
 js/buttons/StepForwardButton.js  | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/js/buttons/StepBackwardButton.js b/js/buttons/StepBackwardButton.js
index 10ef37b5b..dfaf601b7 100644
--- a/js/buttons/StepBackwardButton.js
+++ b/js/buttons/StepBackwardButton.js
@@ -18,8 +18,8 @@ define( function( require ) {
    * @constructor
    */
   function StepBackwardButton( options ) {
-    assert && assert( !options.direction, 'options.direction must not be specified for StepBackwardButton' );
-    StepButton.call( this, _.extend( {}, options, { direction: 'backward' } ) );
+    assert && assert( !options.direction, 'options.direction must be omitted for StepBackwardButton' );
+    StepButton.call( this, _.extend( { direction: 'backward' }, options ) );
   }
 
   sceneryPhet.register( 'StepBackwardButton', StepBackwardButton );
diff --git a/js/buttons/StepForwardButton.js b/js/buttons/StepForwardButton.js
index 7c154e6dc..0c0d98d44 100644
--- a/js/buttons/StepForwardButton.js
+++ b/js/buttons/StepForwardButton.js
@@ -19,8 +19,8 @@ define( function( require ) {
    * @constructor
    */
   function StepForwardButton( options ) {
-    assert && assert( !options.direction, 'options.direction must not be specified for StepForwardButton' );
-    StepButton.call( this, _.extend( {}, options, { direction: 'forward' } ) );
+    assert && assert( !options.direction, 'options.direction must be omitted for StepForwardButton' );
+    StepButton.call( this, _.extend( { direction: 'forward' }, options ) );
   }
 
   sceneryPhet.register( 'StepForwardButton', StepForwardButton );