javascript – Promise.all()是执行函数数组还是在将它们放入数组时执行？

由于await在Array.map或Array.reduce中不起作用,您可以执行以下操作,还是将其视为滥用Promise.all？通常,等待neo4j.session().

// inside a function

const QUERY = 'MATCH (n) RETURN n'
const argsArray = [{ sample: 'sadf' }, { sample: 'sadf' }, { sample: 'sadf' }]

const runQueries = argsArray.map(obj => neo4j.session.run(QUERY, obj.sample))

await Promise.all(runQueries)
      .then(results => results.forEach(result => console.log(result)))

解决方法:

Does Promise.all() execute an array of functions?

没有一系列的承诺

or do they execute when you put them into the array?

确切地说,当你构建Promises时,它们就被执行了.

would this be considered misuse of Promise.all?

不,这完全没问题,它实际上是Promise.all的重点.

但是你可能会(一个接一个而不是并行执行)：

(async function(){

for(const obj of argsArray)
  console.log( await neo4j.session.run(QUERY, obj.sample));

})()

标签：javascript,ecmascript-6,async-await,ecmascript-2017
来源： https://codeday.me/bug/20190608/1195834.html