Only call nodeSelected callback if it has been defined

README.mkdn

@@ -93,9 +93,3 @@ Acknowledgements
 
 Thanks to [Lachlan Donald](http://github.com/lox) for his helpful suggestions and
 feedback.
-
-Additions
-----
-
-This forked version adds a callback (called `nodeSelected` in the jquery
-initializer. This callback is passed the node object.

springyui.js

@@ -31,7 +31,6 @@ jQuery.fn.springy = function(params) {
 	var stiffness = params.stiffness || 400.0;
 	var repulsion = params.repulsion || 400.0;
 	var damping = params.damping || 0.5;
-	
 	var nodeSelected = params.nodeSelected || null;
 
 	var canvas = this[0];
@@ -88,9 +87,10 @@ jQuery.fn.springy = function(params) {
 			// Part of the same bug mentioned later. Store the previous mass
 			// before upscaling it for dragging.
 			dragged.point.m = 10000.0;
-			
-			// Call the nodeSelected code passed during initialization
-			nodeSelected(selected.node);
+
+			if (nodeSelected) {
+				nodeSelected(selected.node);
+			}
 		}
 
 		renderer.start();