手动编写一个promise.all函数
Promise.all = function(iterable) { return new Promise((resolve, reject) => { let result = [] for(const item of iterable) { item.then(data => { result.push(data) }, reason=> { result = reason return }) } resolve(result) }) } //下面是测试用例 let p1 = new Promise((resolve, reject) => { resolve(666) }) let p2 = new Promise((resolve, reject) => { resolve(888) }) let p3 = new Promise((resolve, reject) => { resolve(999) }) let p6 = new Promise((resolve, reject) => { reject(222) }) let p4 = Promise.all([p1, p2, p3]) p4.then(data => { console.log(data) }) //[666, 888, 999] let p7 = Promise.all([p1, p3, p6]) p7.then(data => { console.log(data) }) //222