node.js事件循环何时终止？

Question

I am wondering what are the conditions under which node.js terminates the event loop. How does node.js figure out that no further events are going to be triggered ? For eg in the case of an http client or a file reading application.

Answer 1

i'd recommend you watch this great video Philip Roberts: What the heck is the event loop anyway? | JSConf EU 2014

To explain briefly, Javascript runtime can do one thing at a time, thus it is called "single threaded". However, you have the reason that we can do things concurrently like HTTP requests .. etc. is due what he calls on the video as "Browser APIs" for the browser and for a backend environment like Node.js it is the C++ APIs. Now, any of these "external" API calls like the HTTP client call, is pushed to a task queue. The event loop has one very simple job. It will always take one job from the task queue given that the main callstack is empty and push that to the execution/running stack. So the event loop will terminate when there are no jobs in the task queue (external API calls)

I recommend watching the full video for better understanding :)