Copy files from multiple directories into one directory with Node.js, graceful-fs https://www.npmjs.com/package/graceful-fs and graceful-ncp package https://www.npmjs.com/package/graceful-ncp

copy.js

var fs = require('graceful-fs');
var ncp = require('graceful-ncp').ncp;
// var FileQueue = require('filequeue');
// var fq = new FileQueue(100);
ncp.limit = 16;
fs.readdir(__dirname, function(err, files) {
	for (var i = 0; i < files.length; i++) {
		ncp(files[i], 'C:/path/to/output/folder', function(err) {
			if (err) {
				return console.error(err);
			}
			console.log('done!');
		});
	}
});