jquery ajax: added a comment explaining the last commit.

diff --git a/src/ajax.js b/src/ajax.js
index 2dcf87060313d70359973b1f811dc4d3f5ba13c1..853bcbb43994876ab2cfd098ff0e8bca6c115c9f 100644 (file)
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -470,6 +470,7 @@ jQuery.extend({
                        throw "parsererror";
                        
                // Allow a pre-filtering function to sanitize the response
+               // s != null is checked to keep backwards compatibility
                if( s && s.dataFilter )
                        data = s.dataFilter( data, type );