asyncfs.js

/**
 * NodeJS에서의 비동기 작업 예제
 */
const fs = require('fs');
const util = require('util');

const readdir = util.promisify(fs.readdir);
const writeFile = util.promisify(fs.writeFile);
const readFile = util.promisify(fs.readFile);

const writeLSWithCallback = () => {
    fs.readdir('.', (err, files) => {
        fs.writeFile('ls.json', err => {
            fs.readFile('ls.json', (err, data) => {
                console.log(data.toString());
            })
        })
    })
}

const writeLS = () => {
    return readdir('.')
    .then(result => writeFile('ls.json', JSON.stringify(result)))
    .then(() => readFile('ls.json'))
    .then(content => console.log(content.toString()))
}

const asyncWriteLS = async () => {
    const result = await readdir('.')
    await writeFile('ls.json', JSON.stringify(result));
    const content = await readFile('ls.json');
    console.log(content.toString());
}