你能答对几题?
题目一
const promise = new Promise((resolve, reject) => { console.log(1) resolve() console.log(2) }) promise.then(() => { console.log(3) }) console.log(4)
题目二
const promise1 = new Promise((resolve, reject) => { setTimeout(() => { resolve('success') }, 1000) }) const promise2 = promise1.then(() => { throw new Error('error!!!') }) console.log('promise1', promise1) console.log('promise2', promise2) setTimeout(() => { console.log('promise1', promise1) console.log('promise2', promise2) }, 2000)
题目三
const promise = new Promise((resolve, reject) => { resolve('success1') reject('error') resolve('success2') }) promise .then((res) => { console.log('then: ', res) }) .catch((err) => { console.log('catch: ', err) })
题目四
Promise.resolve(1) .then((res) => { console.log(res) return 2 }) .catch((err) => { return 3 }) .then((res) => { console.log(res) })
题目五
const promise = new Promise((resolve, reject) => { setTimeout(() => { console.log('once') resolve('success') }, 1000) }) const start = Date.now() promise.then((res) => { console.log(res, Date.now() - start) }) promise.then((res) => { console.log(res, Date.now() - start) })
题目六
Promise.resolve() .then(() => { return new Error('error!!!') }) .then((res) => { console.log('then: ', res) }) .catch((err) => { console.log('catch: ', err) })
题目七
const promise = Promise.resolve() .then(() => { return promise }) promise.catch(console.error)
题目八
Promise.resolve(1) .then(2) .then(Promise.resolve(3)) .then(console.log)
题目九
Promise.resolve() .then(function success (res) { throw new Error('error') }, function fail1 (e) { console.error('fail1: ', e) }) .catch(function fail2 (e) { console.error('fail2: ', e) })
题目十
process.nextTick(() => { console.log('nextTick') }) Promise.resolve() .then(() => { console.log('then') }) setImmediate(() => { console.log('setImmediate') }) console.log('end')