在promise中想要接收数据那就的在jsonp的回调函数将其推向已决状态也就是resolve，也可是说jsonp的回调函数就是为啦将promise推向已决阶段
    案例演示

    3. function jsonp(url, cd) {
    4.     return new Promise(resolve => {
    5.         let script = document.createElement('script');
    6.         if (url.includes("?")) {
    7.             url += "&callback=" + cd
    8.         } else {
    9.             url += "?callback=" + cd;
    10.         }
    11.         script.src = url;
    12.         window[cd] = resp => {
    13.             delete  window[cd]
    14.             document.head.removeChild(script)
    15.             resolve(resp)
    16.         }
    17.         document.head.appendChild(script)
    18.     })
    20. }
    22. jsonp("http://developer.duyiedu.com/edu/testJsonp","aaa").then(resp =>{
    23.     console.log(resp)
    24. })