/* 封裝ajax函數 * @param {string}opt.type http連接的方式，包括POST和GET兩種方式 * @param {string}opt.url 發送請求的url * @param {boolean}opt.async 是否為異步請求，true為異步的，false為同步的 * @param {object}opt.data 發送的參數，格式為對象類型 * @param {function}opt.success ajax發送并接收成功調用的回調函數 */  function ajax(opt) {    opt = opt || {};    opt.method = opt.method.toUpperCase() || 'POST';    opt.url = opt.url || '';    opt.async = opt.async || true;    opt.data = opt.data || null;    opt.success = opt.success || function () {};    opt.dataType = opt.dataType || "json";    var xmlHttp = null;    if (XMLHttpRequest) {      xmlHttp = new XMLHttpRequest();    }    else {      xmlHttp = new ActiveXObject('Microsoft.XMLHTTP');    }var params = [];    for (var key in opt.data){      params.push(key + '=' + opt.data[key]);    }    var postData = params.join('&');    if (opt.method.toUpperCase() === 'POST') {      xmlHttp.open(opt.method, opt.url, opt.async);      xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;charset=utf-8');      xmlHttp.send(postData);    }    else if (opt.method.toUpperCase() === 'GET') {      xmlHttp.open(opt.method, opt.url + '?' + postData, opt.async);      xmlHttp.send(null);    }     xmlHttp.onreadystatechange = function () {      if(opt.dataType != 'jsonp'){        if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {          opt.success(xmlHttp.responseText);        }      }else{        //alert(1);         if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {          var oScript = document.createElement('script');          document.body.appendChild(oScript);          var callbackname = 'wangxiao'          oScript.src = opt.url + "?" + postData+'&callback='+callbackname;          window['wangxiao'] = function(data) {            opt.success(data);            document.body.removeChild(oScript);          };        }      }    };  }  export default ajax;