javascript - Executing asynchronous calls in a synchronous manner

Question

I've been trying to wrap my head around this issue for the last hours but can't figure it out. I guess I still have to get used to the functional programming style ;)

I wrote a recursive function that traverses through a directory structure and does things to certain files. This functions uses the asynchronous IO methods. Now I want to perform some action when this whole traversing is done.

How would I make sure that this action is performed after all parse calls have been performed but still use the asynchronous IO functions?

var fs = require('fs'),
    path = require('path');

function parse(dir) {
    fs.readdir(dir, function (err, files) {
        if (err) {
            console.error(err);
        } else {                
            // f = filename, p = path
            var each = function (f, p) {
                return function (err, stats) {
                    if (err) {
                        console.error(err);
                    } else {
                        if (stats.isDirectory()) {
                            parse(p);
                        } else if (stats.isFile()) {
                            // do some stuff
                        }
                    }
                };
            };

            var i;
            for (i = 0; i < files.length; i++) {
                var f = files[i];
                var p = path.join(dir, f);
                fs.stat(p, each(f, p));
            }
        }
    });
}

parse('.');

// do some stuff here when async parse completely finished

Answer 1

Look for Step module. It can chain asynchronous functions calls and pass results from one to another.