js 事件循环中宏任务和微任务执行顺序

async function async1() {
    console.log("async1 start"); //2
    await async2();
    console.log("async1 end"); // 6
}
async function async2() {
    console.log("async2"); // 3
}
console.log("script start"); // 1
setTimeout(function () {
    console.log("setTimeout"); // 8
}, 0);
async1();
new Promise(function (resolve) {
    console.log("promise1"); // 4
    resolve();
}).then(function () {
    console.log("promise2"); // 7
});
console.log("script end"); // 5

script start
async1 start
async2
promise1
script end
async1 end
promise2
setTimeout