// 根據(jù)指定URL發(fā)送一個(gè)JSONP請求 //然后把解析得到的相應(yīng)數(shù)據(jù)傳遞給回調(diào)函數(shù) //在URL中添加一個(gè)名為jsonp的查詢參數(shù),用于指定該請求的回調(diào)函數(shù)的名稱 function getJSONP(url, callback){  //為本次請求創(chuàng)建一個(gè)唯一的回調(diào)函數(shù)名稱  var cbnum = "cb"+getJSONP.counter++;  var cbname = "getJSONP."+cbnum;     if(url.indexof("?") === -1){   url += "?jsonp="+cbname;  }else {   url += "&jsonp="+cbname;  }   var script = document.createElement("script");   getJSONP[cbnum] = function(response){   try{    callback(response);   }finally{    delete getJSONP[cbnum];    script.prentNode.removeChild(script);    }    };    script.src = url;   document.body.appendChild(script);  }  getJSONP.counter = 0;