1. 下面代码的输出结果是什么

   const promise = new Promise((resolve, reject) => {
     console.log(1);
     resolve();
     console.log(2);
   });
   
   promise.then(() => {
     console.log(3);
   });
   
   console.log(4);

2. 下面代码的输出结果是什么

   const promise = new Promise((resolve, reject) => {
     console.log(1);
     setTimeout(() => {
       console.log(2);
       resolve();
       console.log(3);
     });
   });
   
   promise.then(() => {
     console.log(4);
   });
   
   console.log(5);

3. 下面代码的输出结果是什么

   const promise1 = new Promise((resolve, reject) => {
     setTimeout(() => {
       resolve();
     }, 1000);
   });
   const promise2 = promise1.catch(() => {
     return 2;
   });
   
   console.log('promise1', promise1);
   console.log('promise2', promise2);
   
   setTimeout(() => {
     console.log('promise1', promise1);
     console.log('promise2', promise2);
   }, 2000);

4. 下面代码的输出结果是什么

   async function m() {
     const n = await 1;
     console.log(n);
   }
   
   m();
   console.log(2);

5. 下面代码的输出结果是什么

   async function m() {
     const n = await 1;
     console.log(n);
   }
   
   (async () => {
     await m();
     console.log(2);
   })();
   
   console.log(3);

6. 下面代码的输出结果是什么

   async function m1() {
     return 1;
   }
   
   async function m2() {
     const n = await m1();
     console.log(n);
     return 2;
   }
   
   async function m3() {
     const n = m2();
     console.log(n);
     return 3;
   }
   
   m3().then((n) => {
     console.log(n);
   });
   
   m3();
   
   console.log(4);

7. 下面代码的输出结果是什么

   Promise.resolve(1).then(2).then(Promise.resolve(3)).then(console.log);

8. 下面代码的输出结果是什么

   var a;
   var b = new Promise((resolve, reject) => {
     console.log('promise1');
     setTimeout(() => {
       resolve();
     }, 1000);
   })
     .then(() => {
       console.log('promise2');
     })
     .then(() => {
       console.log('promise3');
     })
     .then(() => {
       console.log('promise4');
     });
   
   a = new Promise(async (resolve, reject) => {
     console.log(a);
     await b;
     console.log(a);
     console.log('after1');
     await a;
     resolve(true);
     console.log('after2');
   });
   
   console.log('end');

9. 下面代码的输出结果是什么

   async function async1() {
     console.log('async1 start');
     await async2();
     console.log('async1 end');
   }
   async function async2() {
     console.log('async2');
   }
   
   console.log('script start');
   
   setTimeout(function () {
     console.log('setTimeout');
   }, 0);
   
   async1();
   
   new Promise(function (resolve) {
     console.log('promise1');
     resolve();
   }).then(function () {
     console.log('promise2');
   });
   console.log('script end');