async await

function a1() {  return 1}function a2() {  return new Promise((resolve, reject) => {    setTimeout(() => {      resolve(2)    }, 3000);  })}function a3() {  return 3}async function Dosome() {  console.log(a1());;  console.log(await a2());;  console.log(a3());;
}Dosome()

// 执行async 函数 返回的都是 Promise 对象async function test1() {  return 1}async function test2() {  return Promise.resolve(2)}const result1 = test1()const result2 = test2()console.log(result1);console.log(result2);
// Promise.then 成功的情况对应 await// await 后跟一个promise对象async function test3() {  const p3 = Promise.resolve(3);  p3.then(res => {    console.log("data3", res);  })  const data3 = await p3  console.log("data3", data3);}test3()// await 后跟一个普通值async function test4() {  const data4 = await 4  console.log("data4", data4);}test4()// await 后跟一个函数
async function test5() {  const data5 = await test1()  console.log("data5", data5);}test5()// Promise.catch 成功的情况对应 try...catchasync function test6() {  const p6 = Promise.reject(6)  try {
    const data6 = await p6    console.log("data6", data6);  } catch (e) {    console.log("err", e);  }}test6()