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Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine.

If you're here in 2024 (or later), here's an updated blog...

JavaScript programmers like to use words like, “event-loop”, “non-blocking”, “callback”, “asynchronous”, “single-threaded” and “concurrency”.

"In The Loop" presented by Jake Archibald at JSConf.Asia 2018 Have you ever had a bug where things were happening in the wrong order, or particular style changes were being ignored? Ever fixed that bug by wrapping a section of code in a setTimeout? Ever found that fix to be unreliable, and played around with the timeout number until it kinda almost always worked?

在本文中，我们将解释什么是异步编程，为什么我们需要它，并简要讨论 JavaScript 历史上异步函数是怎样被实现的。

To demonstrate the use of callbacks, promises and other abstract concepts, we’ll be using some browser methods: specifically, loading scripts and performing simple document manipulations.

回调函数是作为参数传递到另一个函数中，然后在外部函数内调用以完成某种例行程序或操作的函数。

"I will call back later!" A callback is a function passed as an argument to another function This technique allows a function to call another function A callback function can run after another function has finished

Introduction: callbacks Promise Promises chaining Error handling with promises Promise API Promisification Microtasks Async/await

Thoroughly understand the limitations of callbacks, how these led to the evolution of promises in JavaScript, and what exactly are promises.

async function 声明创建一个绑定到给定名称的新异步函数。函数体内允许使用 await 关键字，这使得我们可以更简洁地编写基于 promise 的异步代码，并且避免了显式地配置 promise 链的需要。

Yes, JavaScript promises are superbly amazing, but this isn't true until and unless we discover the concept of chaining. But what exactly is chaining?

全局的 setTimeout() 方法设置一个定时器，一旦定时器到期，就会执行一个函数或指定的代码片段。

setTimeout and setInterval are timing events in JavaScript that both allow execution of code at specified time intervals.

We may decide to execute a function not right now, but at a certain time later. That’s called “scheduling a call”.