Event Loop

  • the call stack - one thred == one call stack == one thing at a time
    • push on top, pop off the top
  • Web APIs are threads - where concurrency happens - make calls to.
    • for NodeJS, it's C++ APIs
  • task queue - when Web APIs is ready, it pushes callback to task queue
  • event loop's simple job - look at stack and task queue, if stack is empty, it takes first item from task queue and pushes to stack
  • setTimeout = 0, defer something until the stack is clear
    setTimeout(function cb() {
      console.log('there)
    }, 0)
    • setTimeout is not a guaranteed time to execution, it is mininum time to execution
  • callbacks
    1. any function that another function calls
    2. async func - one that will get pushed to callback queue

To Review

  1. Loupe↩