​

function resolveAfter5Seconds(para) { 

  let d = new Date();

  console.log('當前秒數：' + d.getSeconds());

  return new Promise(resolve => {

    setTimeout(() => {

      if(para == 20) {

        console.log('秒數：' + d.getSeconds() + '輸出 Y了！');  

      } else {

        console.log('秒數：' + d.getSeconds() + '輸出 X了！');

      }

      resolve(para);

    }, 5000);

  });

}

​

async function f1() {

  //這邊的await順序，可以理解 await的操作模式

  let y = await resolveAfter5Seconds(20);

  let x = await resolveAfter5Seconds(10);

  console.log(x); // 10

  console.log(y); // 20

}

f1();

​