// Serialize the key/values
for ( var j in a )
// If the value is an array then the key names need to be repeated
- if ( a[j].constructor == Array )
+ if ( a[j] && a[j].constructor == Array )
jQuery.each( a[j], function(){
s.push( encodeURIComponent(j) + "=" + encodeURIComponent( this ) );
});