- while ( (prop = arguments[a++]) != null )
- // Extend the base object
- for ( var i in prop ) target[i] = prop[i];
+
+ for ( ; a < al; a++ )
+ // Only deal with non-null/undefined values
+ if ( (prop = arguments[a]) != null )
+ // Extend the base object
+ for ( var i in prop ) {
+ // Prevent never-ending loop
+ if ( target == prop[i] )
+ continue;
+
+ // Recurse if we're merging object values
+ if ( typeof prop[i] == 'object' && target[i] )
+ jQuery.extend( target[i], prop[i] );
+
+ // Don't bring in undefined values
+ else if ( prop[i] != undefined )
+ target[i] = prop[i];
+ }