how to convert recursive callback function to async-await format

Question

I want to convert recursive callback function to async-await format, the following is the code,

function findFiles(currentDirPath, callback) {
    fs.readdir(currentDirPath, function (err, files) {
        if (err) {
            throw new Error(err);
        }
        files.forEach(function (name) {
            var filePath = path.join(currentDirPath, name);
            var stat = fs.statSync(filePath);
            if (stat.isFile()) {
                callback(filePath, stat);
            } else if (stat.isDirectory()) { //if directory call function
                findFiles(filePath, callback);
            }
        });
    });
}

and this is how i call function,

findFiles('./logs', function(route){
    console.log(route);
});

following is the progress I've made, I don't know is it the right way or not, please guide me.

var bundle = [];
var findFiles = async function (root) {

    let files = await readFile(root);
    for(let inx in files){
        var filePath = path.join(root, files[inx]);
        var stat = fs.statSync(filePath);

        if (stat.isFile()) {
            bundle.push(filePath);
        } else if (stat.isDirectory()) {
            await findFiles(filePath);
        }

    }
    return bundle;
};

let readFile = function(dir){
    return new Promise((resolve, reject) => {
        fs.readdir(dir, function(err,files){
            if (!err) {
                resolve(files); 
            } else {
                reject(err);
            }
        });
    });
};

this is how i calling file,

 let files = await findFiles('./logs');

Well, have you tried anything? Also keep in mind that async/await only works with promises. — Yury Tarabanko
– Yury Tarabanko, Commented Jul 23, 2018 at 10:20
What did you try and what was the problem? Obviously, you need to use promises. Use for..of instead of forEach, it's obsolete. — Estus Flask
– Estus Flask, Commented Jul 23, 2018 at 10:20

Yury Tarabanko · Accepted Answer · 2018-07-23 10:47:44Z

1

First you need to promisify fs functions or use fsPromises-* functions if you are ready to use experimental API..

const { promisify } = require('util')
const fs = require('fs')

const readdir = promisify(fs.readdir)
const stat = promisify(fs.stat) // to use instead of statSync

Then you could do something like this.

async function forEachFile(dir, fn) {
  const files = await readdir(dir)

  for( const item of files) {
    const filePath = path.join(dir, item)
    const stats = await stat(filePath);

    if (stats.isFile()) {
       await fn(filePath, stats) // in case fn is async
    } else if(stats.isDirectory()) {
       await forEachFile(filePath, fn)
    }
  }
}

edited Jul 23, 2018 at 10:47

answered Jul 23, 2018 at 10:34

Yury Tarabanko

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1 Comment

Estus Flask Over a year ago

Node 10 users don't need promisification step, there's fs.promises.

Mr. J · Accepted Answer · 2018-07-23 11:28:54Z

1

very easy to understand,

this is how I call function,

await (async ()=> {
   return new Promise(async function(resolve, reject) {
       await findFiles(configs.server.routes.root, function(route){
           console.log(route)
           //do things
        });
    });
})();

var findFiles = async function (root, callback) {

    let files = await readFile(root);
    for(let inx in files){
        var filePath = path.join(root, files[inx]);
        var stat = fs.statSync(filePath);

        if (stat.isFile()) {
            callback(filePath);
        } else if (stat.isDirectory()) {
            await findFiles(filePath, callback);
        }

    }
};

let readFile = function(dir){
    return new Promise((resolve, reject) => {
        fs.readdir(dir, function(err,files){
            if (!err) {
                resolve(files); 
            } else {
                reject(err);
            }
        });
    });
};

this solution is working perfectly fine for me.

answered Jul 23, 2018 at 11:28

Mr. J

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1 Comment

Mr. J Over a year ago

@YuryTarabanko what is your opinion regarding this solution?

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