Question

I’m using this asynchronous recursive function to iterate through a directory’s files and folders, and when a .css file is found, I append data to a file called ‘common.css’.

var walk = function(dir, done) {
 var results = [];

 fs.readdir(dir, function(err, list) {
      if (err) return done(err);
      var pending = list.length;
      if (!pending) return done(null);
      list.forEach(function(file) {
           file = dir + '/' + file;
           fs.stat(file, function(err, stat) {
                if (stat && stat.isDirectory()) {
                     minimizer(file, function(err, res) {
                          results = results.concat(res);
                          if (!--pending) done(null);
                     });
                } else if(file) {
                     fs.open('common.css', 'a', 666, function( err, id ) {
                         fs.write( id, 'hello', null, 'utf8', function(){
                             fs.close(id, function(){
                                  console.log('file closed');
                             });
                         });
                     });
                }
                if (!--pending) done(null);
           });  
      });
});   }

The problem is that, being asyncronous, I sense that there are times, where several instances of the function are writing to the file at the same time. Is there any way I can control this flux and queue the writing tasks?

The purpose of this code is to merge the .css files that are found in the directory. I cannot use external tools in this project.

EDIT ANSWER: Well, for this purpose, I can just gather the paths of all .css files I want to merge, and after I have them all, call a syncronous function to write them.

That’s what the

var results = []

is there for. I just realized it.

Answer 1

Well, I ended up using a serial recursive function for the same purpose. It solved the problem . In the answer of user “chjj” in taken from node.js fs.readdir recursive directory search

var fs = require('fs');
var walk = function(dir, done) {
  var results = [];
  fs.readdir(dir, function(err, list) {
    if (err) return done(err);
    var i = 0;
    (function next() {
      var file = list[i++];
      if (!file) return done(null, results);
      file = dir + '/' + file;
      fs.stat(file, function(err, stat) {
        if (stat && stat.isDirectory()) {
          walk(file, function(err, res) {
            results = results.concat(res);
            next();
          });
        } else {
          results.push(file);
          next();
        }
      });
    })();
  });
};

Thank you all for your suggestions 🙂