npm batch demo

batch.js

var Batch = require('batch')
    , batch = new Batch;

var self = this;

batch.concurrency(4);

var ids = [0,1,2,3];
var fleetName = ['加賀', '赤城', '島風', '出雲'];

function organizeFleet(id, done) {
    var fleet = fleetName[id];
    console.log('organized', fleet);
    done(null, fleet);
}

ids.forEach(function(id) {
    batch.push(function(done) {
        organizeFleet(id, done);
    });
});

batch.on('progress', function(e) {
    console.log('progress', e.complete / e.total * 100, '%');
});

batch.end(function(err, fleets) {
    console.log('results', fleets);
});