create folder and single file on to it

index.js

const path = require('path');
const mkdirp = require('mkdirp-promise');
const fs = require('fs-extra')

let dirs = [
    "foldername1",
    "foldername2",
    "foldername3"
];

const file = 'json.txt'

const makeAllDirs = (root, list) => {
    return list.reduce((p, item) => {
        return p.then(() => {
            return mkdirp(path.join(root, item));
        });
    }, Promise.resolve());
}

makeAllDirs(__dirname, dirs).then(() => {
    // all done here
    dirs.forEach(function(element) {
        console.log(element);
        fs.outputFile('./' + element + '/' + file, 'hello!', err => {})
    });
    }).catch(err => {
    // error here
 });