jquery getJSON导致的页面阻塞

js中单点登录使用了如下代码：

getJSON("http://sso.jcloud.com/setCookie?t=sso.ehaoyao.com&callback=?");

由于某种原因，目标服务器停止了服务，导致请求超时，无法执行后续的js，直接导致页面不能加载

jQuery.getJSON( url [, data ] [, success( data, textStatus, jqXHR ) ] )

• url
  Type: String
  A string containing the URL to which the request is sent.
• data
  Type: PlainObject
  A plain object or string that is sent to the server with the request.
• success( data, textStatus, jqXHR )
  Type: Function()
  A callback function that is executed if the request succeeds.

If the URL includes the string "callback=?" (or similar, as defined by the server-side API), the request is treated as JSONP instead.

By default, all requests are sent asynchronously (i.e. this is set to true by default). If you need synchronous requests, set this option to false. Cross-domain requests and dataType: "jsonp" requests do not support synchronous operation. Note that synchronous requests may temporarily lock the browser, disabling any actions while the request is active.

getJSON默认是异步的，但是跨域时不支持异步，正是因为我的请求时跨域了的，所以同步请求时被阻塞了，因此出现页面不能加载。