Promise vs setTimeout [英] Promise vs setTimeout

问题描述

我在以下代码中观察到：

I've observed that in the following code:

setTimeout(function(){console.log('setTimeout')});
Promise.resolve(1).then(function(){console.log('promise resolve')})

无论我执行多少次，promise回调总是在setTimeout之前记录。

No matter how many times I execute this, the promise callback always logs before the setTimeout.

我的理解是两个回调都被安排在执行到下一个滴答，我真的不明白发生了什么使得承诺总是优先于超时。

My understanding is that both callbacks are scheduled to be executed to the next tick, and I don't really understand what is going on that makes the promise always take precendence over the timeout.

推荐答案

简短答案Promise比事件循环堆栈中的setTimeout回调函数（或我如何理解）具有更好的优先级。

Short answer Promises have better priority than setTimeout callback function in event loop stack(or how i understand it).

长答案观看此视频。很有帮助。希望这会有所帮助。

Long answer watch this video. Very helpful. Hope this helps.

https：// www.youtube.com/watch?v=8aGhZQkoFbQ

感谢@MickJuice提供有关事件循环的新视频和更新视频。

Thanks @MickJuice for new and updated video for event loop.

https://www.youtube.com/watch?v=cCOL7MC4Pl0

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