async function chain

async_function_chain.js

function chain(prev = null) {
  const cur = () => {
    if (cur.prev) {
      cur.prev.next = cur;
      cur.prev();
    } else {
      cur.forward();
    }
  }
  cur.prev = prev;
  cur.fn = null;
  cur.args = null;

  cur.do = (fn, ...args) => {
    cur.fn = fn;
    cur.args = args;
    return chain(cur);
  };

  cur.forward = () => {
    console.log(cur.fn, cur.args);
    if (cur.fn) cur.fn(cur.args, () => {
      console.log(1);
      if (cur.next) cur.next.forward();
    })
  }
  return cur;
}

function foo(item) {
  console.log(item);
}

const c1 = chain()
  .do(foo, {a: 1, b: 2})

c1()