在 nodejs/js 中组织异步等待函数

Question

I often use this pattern in organising my code in js/nodejs

(async function(){

    let resultOne = await functionOne();
    let resultTwo = await functionTwo();

    return {
        resultOne: resultOne,
        resultTwo: resultTwo,
    }

}()).then(r=>{
    console.log(r);
}).catch(err=>{
    console.log(err);
});

But i want to do functionOne and functionTwo in parallel, not waiting for previos to return promise. Only waiting last one for return. How can i achieve it?

Answer 1

If you don't want them to run sequentially, use Promise.all :

Promise.all([functionOne(), functionTwo()]).then(([resultOne, resultTwo]) => {
    console.log({resultOne, resultTwo});
}).catch(err => {
    console.log(err);
});

or

(async function(){
    const [resultOne, resultTwo] = await Promise.all([functionOne(), functionTwo()]);
    return {resultOne, resultTwo};
}()).then(r => {
    console.log(r);
}).catch(err => {
    console.log(err);
});

Answer 2

You can await a Promise.all():

(async function(){

    const results = await Promise.all([functionOne(), functionTwo()])

    return {
        resultOne: results[0],
        resultTwo: results[1],
    }

}()).then(r=>{
    console.log(r);
}).catch(err=>{
    console.log(err);
});