浅析JSONP技术原理及实现

var requestJsonp = function (opt) {var funName, script;/** step1 创建_callback方法*/ //_callback函数名funName = '_cb' + (Math.random() * 1000000);//创建_callback方法window[funName] = function (data) {if (typeof opt.success == 'function') {opt.success(data);}window[funName] = null;delete window[funName];document.body.removeChild(script);script = null;};/** step2 插入script标签*/script = document.createElement('script');script.type = 'text/javascript';script.src = opt.url + (opt.url.indexOf('?') > -1 ? '&' : '?') + '_callback=' + funName;document.body.appendChild(script);/** step3 服务器输出js* 服务器应接受url参数中_callback的值,作为函数名执行输出js* 类似输出* _callback({"name":"jsonp","description":"jsonp test"});*/ /** 处理error*/script.addEventListener('error', function () {window[funName] = null;delete window[funName];if (typeof opt.error == 'function') {opt.error();}document.body.removeChild(script);script = null;});};requestJsonp({url: 'http://www.url.org?tid=Jsx2',success: function (data) {console.log(data);},error: function () {console.log('request error!');}});