使用nodeAPI时遇到过异步问题解决

const fs = require('fs')
const readFileFn = () => {
	let demo = []
  fs.readFile('./config.JSON', async function (err, date) {
    Promise.all([Promise.resolve(() => 456)]).then(res => {
      demo = res
    })
  })
  return demo
}
console.log('end', readFileFn()) // 要输出456

const fs = require('fs')
const readFileFn = (callback) => {
  fs.readFile('./config.json', async function (err, date) {
    Promise.all([Promise.resolve(456)]).then(res => {
      callback(res)
    })
  })
}
readFileFn(data => console.log(data)) // [ 456 ]

const fs = require('fs')
const readFileFn = async () => {
  const [result] = await Promise.all([
    new Promise(resolve => fs.readFile('./config.json', (err, data) => resolve(456))),
  ])
  return result
}
readFileFn().then(res => console.log(res)) // 456

const readFileFn = () => {
  return new Promise(resolve => {
    fs.readFile('./config.json', async function (err, date) {
      Promise.all([Promise.resolve(456)]).then(res => {
        resolve(res)
      })
    })
  })
}
readFileFn().then(console.log) // [456]
// readFileFn().then(res => console.log(res))