mui 浏览器跨域实现

from:http://ask.dcloud.net.cn/question/17373

APP开发时 是不需要JSONP支持的 mui本身就支持 但是 如果是微信或者浏览器的普通模式就不支持。所以贴出以下代码 大家可参考使用。（参考了zepto）

var jsonpID = 0;
    $.ajaxJSONP = function(url, options){
        if (typeof url === "object") {
            options = url;
            url = undefined;
        }
        var options = $.extend({}, options || {})
        for (var key in $.ajaxSettings) {
            if (options[key] === undefined) {
                options[key] = $.ajaxSettings[key];
            }
        }
         options.url = appendQuery(options.url, "_=" + Date.now())

        options.url = appendQuery(options.url,
          options.jsonp ? (options.jsonp + "=?") : options.jsonp === false ? "" : "callback=?")
        var _callbackName = options.jsonpCallback,
      callbackName = ($.isFunction(_callbackName) ?
        _callbackName() : _callbackName) || ("jsonp" + (++jsonpID)),
      script = document.createElement("script"),
      originalCallback = window[callbackName],
      responseData,
      abort = function(errorType) {
       script.parentNode.removeChild(script)
        if (callbackName in window) window[callbackName] = empty
        ajaxComplete("abort", xhr, options)
      },
      xhr = { abort: abort }, abortTimeout;
        if (options.error) script.onerror = function() {
          xhr.abort()
          options.error()
        }

        window[callbackName] = function(data){
          clearTimeout(abortTimeout)
          script.parentNode.removeChild(script)
          delete window[callbackName]
          ajaxSuccess(data, xhr, options)
        }

        serializeData(options)
        script.src = options.url.replace(/=?/, "=" + callbackName)
        document.head.appendChild(script)

        if (options.timeout > 0) abortTimeout = setTimeout(function(){
            xhr.abort()
            ajaxComplete("timeout", xhr, options)
          }, options.timeout)    
        return xhr
      }