function loadTracks() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve(["模板字符串", "模块化", "async/await"]);
    }, 700);
  });
}

const status = document.getElementById("status");
const output = document.getElementById("output");

status.textContent = "加载中...";

loadTracks()
  .then((tracks) => {
    status.textContent = "加载完成";
    output.textContent = tracks.join("\n");
  })
  .catch(() => {
    status.textContent = "加载失败";
  });