15.手写 JsonP

function request(options) {
  return new Promise((resolve, reject) => {
    const { url, timeout } = options;
    let requestNode = document.createElement("script");
    //创建请求
    requestNode.src = url;
    // <script src="">
    Promise.race([
      setTimeout(function () {
        reject("没有返回数据");
      }, timeout),
      (window.cb = (result) => {
        resolve(result);
      }),
    ]);
    // js加载异常的情况
    jsNode.addEventListener(
      "error",
      () => {
        delete window[callbackName];
        document.body.removeChild(jsNode);
        reject("JavaScript资源加载失败");
      },
      false
    );
    // 添加js节点到document上时，开始请求
    document.body.appendChild(requestNode);
  });
}

request({
  url: "https://suggest.taobao.com/sug?code=utf-8&q=%E5%8D%AB%E8%A1%A3&callback=cb",
  timeout: 2000,
})
  .then((result) => {
    console.log(result);
  })
  .catch((err) => {
    console.log(err);
  });