JS JSONP 函數封裝

轉載自 https://my.oschina.net/shuaihong/blog/1542554

myJsonp = function(url,data,callback){
            
    var fnName = 'myJsonp_' + Math.random().toString().replace('.','');
    
    //定義一個全局回調函數
    window[fnName] = callback;
    
    //初始化序列化參數
    var querystring = '';

    for(var attr in data){

        querystring += attr + '=' + data[attr] + '&';

    }
    //動態創建script標簽
    var script = document.createElement('script');
    
    //后台接受回調函數，並調用
    script.src = url + '?' + querystring + 'callback=' + fnName;
    
    //處理完畢之后,刪除script標簽，否則多次請求，頁面會存在多個script標簽
    script.onload = function(){    

        document.body.removeChild(script);

    }
    
    document.body.appendChild(script);
}