FF 下 prototype.js 1.5 与 json.js 的冲突

CODE:

<script language="javascript">
function ajaxComplete(x){
  alert('ok');
}

function ajaxException(request, exception){
  alert(exception);
}
  new Ajax.Request('/test.html',{method: 'get',onSuccess :ajaxComplete,onException:ajaxException});
</script>