Evaluation order vs. concurrency

async-assign.js

(async () => {
  // small function that resolves after t ms
  const sleep = t => new Promise(resolve => setTimeout(resolve, t));

  let state = {
    counter: 0,
    running: true
  };

  const setCounter = v => {
    const prevCounter = state.counter;
    state.counter = v;
    console.log(prevCounter, "=>", v);
  };

  const getOne = async () => {
    await sleep(1000);
    return 1;
  };
  const addOneAsync = async () => {
    // Uncomment one:
    // setCounter(state.counter + (await getOne()));
    // setCounter((await getOne()) + state.counter);
  };
  addOneAsync();
  await sleep(500);
  setCounter(state.counter + 1);
  await sleep(500);
  setCounter(state.counter + 1);
})();