breaking down an event loop

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onto today’s topic: breaking down an event loop ➿ 

even if coding is edging closer and closer to becoming obsolete, knowing what components make up the software you want to create is still important. with that being said, i’m going to explain what an event loop is.

in one sentence, it’s an important frontend (user-facing) javascript concept that enables web pages to multitask and remain responsive while handling other functions simultaneously.

think of the event loop like a waiter at a restaurant. 🍽️ 

1. the waiter is taking a number of orders and tending to different tables at the same time (much like different tasks in software like button clicks and api calls)

2. those orders are sent to the kitchen and the waiter moves on to other tasks in the meantime until the food is ready (similar to fetching data from a server)

why is this important? well, javascript by default actually only handles one thing at a time from top to bottom. it’s single-threaded. with the event loop, paired with asynchronous programming, your code can perform multiple tasks as once without waiting for the previous job to finish.

an event loop achieves this by continuously checking: 1) if the call stack is empty and 2) if there are pending tasks in the callback queue. if both are true, the event loop moves the task from the callback queue to the call stack for execution. 🪓 

think of it as a list of orders posted up on the window. 1) is the waiter not currently taking any orders? 2) are there tables waiting for their order to be taken? if yes for both, one of those pending orders will now be on the waiter’s radar and will be taken care of.

most programming concepts are just processes we use in our daily lives but just structured in a way for computers to execute in a similar fashion. :)

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