What is the Event Loop?

In one single sentence, moving events from the task queue to the call stack is called the “event loop”. But in order to fully understand how the event loop works, you also need to understand three other things in JavaScript:

• The stack: The order in which your code is being executed, is handled by the call stack. You can think of it as an array that holds a list of command on what to execute next.
• The web API thread: Everything that is not part of the JavaScript engine, is handled by a separate thread. Think of the various functions you get in the browser, such setTimeout or a Promise.
• The task queue: Everything that is waiting to be executed is stored in the task queue. Such as a callback funcion from a setTimeout. Until the task queue is empty again, the event loop will process the next message in the queue and puts it into the stack.

What is The Event Loop in JavaScript?Explaining the event loop through the example of setTimeoutYou may have heard that JavaScript has a thing called the “event loop”. But what is it actually and what does it really mean?Learn More

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Resources:

• The concurrency model and the event loop