Ajax based actions cause js errors with synchronous calls

The docs describe If you for some reason or another need synchronous processing (that‘ll block the browser while the request is happening), you can specify options[:type] = :synchronous.

If I make a call to any helper aka drop_receiving_element with type => :synchronous, the asynchronous is set as expected, but an additional argument type:synchronous is added.

Droppables.add("drop_zone", {onDrop:function(element){new Ajax.Request('/containers/dropped', {asynchronous:false, evalScripts:true, parameters:'id=' + encodeURIComponent(element.id)})}, type:synchronous}

This causes a js error since synchronous isn't defined as a JS variable. Alternate variations of :synchronous => true or :asynchronous => false don't work, although the docs don't say they should anyway.