新增无答案版

Promise面试题归总（无答案版）.md

@@ -0,0 +1,179 @@
+1. 下面代码的输出结果是什么
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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
+
+   ```js
+   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');
+   ```