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.suess == 'function') {
opt.suess(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://.url.?tid=Jsx2',
suess: function (data) {
console.log(data);
},
error: function () {
console.log('request error!');
}
});