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This article focuses on "what is synchronous and asynchronous programming in NodeJS". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn what synchronous and asynchronous programming is in NodeJS.

What is an event loop?

You may have guessed it right-- Node uses event loops to process requests in a NodeJS environment. But first, let's learn some basic terms that help us understand the whole mechanism.

An event loop is an event listener that runs in a NodeJS environment and is ready to listen, handle, and output events at any time.

Events can be anything from mouse clicks to keystrokes or timeouts.

What is synchronous and asynchronous programming?

Synchronous programming means that the code runs in the order it defines. In a synchronizer, the next line is executed when a function is called and a value is returned.

Let's use this example to understand:

Const listItems = function (items) {items.forEach (function (item) {console.log (item)})} const items = ["Buy milk", "Buy coffee"] listItems (items) The output will look like this: "Buy milk"Buy coffee"

In this example, when the listItems (items) function is called, it iterates through the project array. Console.log (item) first calls the function for the first item of the array and prints "Buy milk". Then console.log (item) executes again, this time passing the second item of the array and printing "Buy coffee."

So you can say that this function is executed in the order it defines.

Asynchronous programming, on the other hand, refers to code that is not executed sequentially. These functions are not performed in the order they are defined in the program, but only when certain conditions are met.

For example, setTimeOut () executes a task after a predefined millisecond delay.

SetTimeOut (function () {return (console.log ("Hello World!"))}, 3000)

These functions do not run line by line, but only when they need to be run, regardless of the function's declaration. In this case, when all synchronization functions are completed, the function will run automatically after 3 seconds.

Note: asynchronous functions run and execute only after all synchronous functions have been executed. Until then, they will be processed in the background.

If you want to learn more about NodeJS and asynchronous programming, you can refer to this article

But how does NodeJS handle asynchronous functions in the background and run all synchronous functions first? All of these mechanisms can be easily explained with NodeJS event loops.

At this point, I believe you have a deeper understanding of "what synchronous and asynchronous programming is in NodeJS". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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