Queue, thread, stack, task, job, flow, stream

nano-queue.js

const Queue = () => {
  let idle = true;
  const stack = [],
  fx = (...job) => {
    stack.push(...job);
    if(idle)
      (async () => {
        idle = false;
        while(stack.length)
          await stack.shift()();
        idle = true;
      })();
  };
  Object.defineProperty(fx,'pending',{get: ()=>stack.length});
  return fx;
};

// ======= Test ==========

const wait = ms => new Promise(res => setTimeout(res,ms));

const Job = id => async ()=>{
  console.log('Job started: ' + id);
  await wait(1000);
  console.log('Job finished: ' + id);
};

const queue = Queue();

queue(Job(1));
queue(Job(2));
queue(Job(3),Job(4),Job(5));
queue(Job(6));
queue(Job(7),Job(8));

console.log(queue.pending);
setTimeout(()=>console.log(queue.pending),2500);