NodeJS

[ZhiyuanSun]

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[ZhiyuanSun]

NodeJS Eventloop

https://segmentfault.com/a/1190000012258592
kaola-fed/blog#234
https://blog.csdn.net/liwusen/article/details/79509288

Timer -> I/O callbacks -> idle, prepare-> poll -> check -> close callbacks

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"execute" setTimeout setInterval callback as soon as possible [1,2147483647] ->

other system callbacks (except setImmediate()), not user callback ->

idle for internal use ->

• has timer? check timer and run whenever poll is clean
• no timer? Clean up poll queue synchronically.

DONE CLEANING POLLING QUEUE

• setimmediate()? go!
• not setimmediate()? wait for new event, node block ->

check, setimmediate callback ->

close callbacks

nextTick/Promise are in between of stages, has it's own queue, will clean up

[ZhiyuanSun]

Promise tips

https://zhuanlan.zhihu.com/p/25178630

1. .then and .catch only accept callbacks, otherwise value penetration
2. .catch looks like the second argument of .then, but .catch can catch the error from first callback in .then

[ZhiyuanSun]

Web browser Eventloop

while(true) {
    macroQueue.shift()
    microQueue.all() // DOM mutation (max 60Hz), Promise
}