What is Event loop in Javascript and what it does?

What is Javascript?

Let's clear this up first. Javascript is a programming language used to develop web apps. It is also used to develop cross-platform desktop and mobile applications (through frameworks).

JS is Single-Threaded, non-blocking, and supports asynchronous programming.

To know about Event-loop and its working we need to know about a few other things, i.e Call Stack and Task Queue.

What is Call Stack

To be short and concise :

• The working of the call stack is the same as the stack data structure.

• The stack data structure can be equated with a stack of plates.

• The last item pushed gets popped (deleted) first

• Heap is used for allocating memory.

• Tasks are appended to call stack in a sequential manner and removed in the same fashion.

  let's see a simple example of the working of call stack:

    function answer(){
        say("Good Morning");
    }
    function say(text){
        console.log(text)
    }
    answer()
    //output : Good Morning
  

  

What is a Task-Queue?

• Since Javascript is single-threaded, it can only do one task at a time; hence, in cases where multiple tasks need execution, they get pushed into the task queue.

• The tasks in the task queue wait for their turn for execution.

• This is where the Event Loop comes in, its job is to push the task from the task queue to the call stack.

This was a simple explanation of the basics of Event-loop. Its internal working is a different monster that can be covered another day. Feel free to post a comment.