怎么让异步结果按顺序填入到数组中呢？ Promise Promise.all()

Question

const p1 = () => {

return new Promise((resolve, reject) => {

setTimeout(function () {

resolve("p1");

}, 2000);

})

}

const p2 = () => {

return Promise.resolve(2);

}

const p3 = () => {

return Promise.resolve(3);

}

  

promiseAll([p1(), p2(), p3()]).then(res => {

console.log(res);

});


function promiseAll(arr) {

return new Promise( (resolve, reject) => {

let result = [];

for (var i = 0; i < arr.length; i++) {

arr[i].then(res => {

result.push(res); // 怎么让这个 res按循序填入数组中呢？

if (result.length == arr.length) {

resolve(result);

}

}).catch(err => {

reject(err);

})

}

})

}

Answer 1

Promise.all([p1(), p2(), p3()])
    .then(function(result){
        console.log(result) // ["p1",2,3]
    })

Answer 2

Promise.allSettled()

Answer 3

使用 async ... await 格式转换成按顺序执行

async function(){
    const a = await Promise();
    const b = await Promise();