Simple javascript thread pool example

threadPool.js

ThreadPool = function(script, size) {
  this.threads = [];
  this.tasks = [];
  for (var ithread = 0; ithread < size; ithread++) {
    this.threads.push(new lxst.FilterThread(script, this));
  }
};

ThreadPool.prototype.queueTask = function(task, callback) {
  const task = {task: task, callback: callback};
  if (this.threads.length > 0) {
    var thread = this.threads.shift();
    thread.run(task);
  } else {
    this.tasks.push(task);
  }
};

ThreadPool.prototype.afterTask = function(thread) {
  if (this.tasks.length > 0) {
    thread.run(this.tasks.shift());
  } else {
    this.threads.push(thread);
  }
};

Thread = function(script, pool) {
  this.worker = new Worker(script);
  this.worker.addEventListener('message', this.onmessage.bind(this));
  this.pool = pool;
  this.callback = null;
};

Thread.prototype.run = function(task) {
  this.worker.postMessage(task.task);
  this.callback = task.callback;
};

Thread.prototype.onmessage = function(message) {
  this.callback(message.data);
  this.callback = null;
  this.pool.afterTask(this);
};

var pool = new ThreaPool("script.js", 2);
pool.addTask(task, function(result) { console.log(result); });