async await阻塞

今天在使用async与await的时候，突然想到await阻塞的时候会不会影响到整个线程，所以做了个小实验

代码：

const doSomeThing = async () => {
  console.log('start do some thing');
  await doA();
  await doB();
  console.log('do some thing done');
};

const doAnotherThing = () => {
  console.log('do another thing');
};

const doA = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('do a');
      resolve();
    }, 0);
  });
};

const doB = () => {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      console.log('do b');
      resolve();
    }, 0);
  });
};
doSomeThing();
doAnotherThing();

输出结果:

start do some thing
do another thing
do a
do b
do some thing done

所以async,await 的阻塞只在该函数作用域有效,本质上还是异步回调调用。