event loop

task queue中取任务

同步任务立即执行

异步任务挂起来，可以执行时放入task queue

执行完再去取任务

// 同步任务中此为microtask, 会在本轮事件循环的末尾执行
Promise.resolve().then(() => {
    
    console.log('bbb');
})

Tasks execute in order, and the browser may render between them
Microtasks execute in order, and are executed：
after every callback, as long as no other JavaScript is mid-execution
at the end of each task

摘录自第一篇参考文章

• 参考

Tasks, microtasks, queues and schedules

JavaScript 运行机制详解：再谈Event Loop

js执行机制（promise,setTimeout执行顺序）