code/promises/exercise/main.js
/*
List the content of the folder, filter out the files only
then copy to the output folder.
*/
const fs = require('fs')
const path = require('path')
const util = require('util')
const readFile = util.promisify(fs.readFile)
const writeFile = util.promisify(fs.writeFile)
const readdir = util.promisify(fs.readdir)
const stat = util.promisify(fs.stat)
const mkdir = util.promisify(fs.mkdir)
const outputFolder = './output'
function isFile(f) {
return stat(f).then(d => (d.isFile() ? f : ''))
}
function filterFiles(list) {
return Promise.all(list.map(isFile)).then(files => files.filter(v => v))
}
function readWrite(result) {
const files = result[1]
return Promise.all(
files.map(f => {
return readFile(f).then(content =>
writeFile(path.join(outputFolder, f), content)
)
})
)
}
const getFiles = readdir('./').then(filterFiles)
Promise.all([mkdir(outputFolder), getFiles])
.then(readWrite)
.then(() => console.log('done!'))
.catch(e => console.log(e))