Node.js中的异步函数

Question

It's just a little question about asynchronous function in nodejs and the good way to create them. the following takes in parameters a repository and an extension name and return the list of the files with the given extension in the given repository

to run

$ node app /path/to/some/reposity someExtension

module.js file

//modules.js
var fs = require('fs');
var path = require('path');
module.exports = function(dir, ext, callback){
    //do something
    fs.readdir(dir, function(err, data){
        if(err){
            //EDIT
            process.nexTick(function(){
                callback(err);
            });
            //
        }
        if(data){
            var compteur = 0;
            var block = [];
            for(var i =0 ; i < data.length ; i++){
                if(path.extname(data[i]).slice(1) == ext){
                    block[compteur]= data[i];
                    compteur++;
                }
            }
            //EDIT
            process.nextTick(function(){
                callback(null, block);
            });
            //
        }

    });
};

app.js file

//app.js
var dir = process.argv[2];
var ext = process.argv[3];
var module = require('./module');

module(dir, ext, function(err, data){
    if(err) { throw err;}
    var dl = data.length;
    for(var i = 0 ; i < dl ; i++){
        console.log(data[i]);
    }
});

I just wanted to know if it's the good way to do things or if there a better one. Thanks in advance.

I find this nice tutorial on asynchronous function in NodeJS http://howtonode.org/understanding-process-next-tick

Answer 1

The standard way to program asynchronously is to use callbacks, which is what you've doing. Since the callback is nested within an asynchronous function, it will be queued once the callstack is empty.

Also, don't name any variables module . It is a global variable which should not be overwritten.