所有的 Node.js 回调函数都是异步的吗? [英] Are all Node.js callback functions asynchronous?

问题描述

我正在学习 Node.js，在每个教程中我听到的都是Node 是异步的，没有阻塞！"

I'm working on learning Node.js and all I hear in every tutorial is "Node is asynchronous and no -blocking!"

我听说在常规浏览器 JavaScript 中，只有某些事情(例如 AJAX 调用)可以异步或非阻塞(使用回调)... Node.js 也是如此，还是所有 Node.js 回调都是如此函数实现异步/非阻塞?

I've heard in regular browser JavaScript only certain things such as AJAX calls can be made asynchronous or non-blocking (using callbacks)... Is this true of Node.js as well, or are all Node.js callback functions made asynchronous/non-blocking?

推荐答案

所有的 Node.js 回调函数都是异步/非阻塞的吗?

are all Node.js callback functions made asynchronous/non-blocking?

没有.通常只有 I/O 是异步的，但许多其他回调是同步的.始终检查文档.

No. Only I/O is usually asynchronous, but many other callbacks are synchronous. Always check the docs.

异步函数示例:

• 异步文件系统访问(不过他们有没有回调的同步副本)
• 定时器(setTimeout)
• process.nextTick, setImmediate
• 大多数数据库连接
• 网络连接
• 承诺

• Async Filesystem access (they have sync counterparts without callbacks, though)
• Timers (setTimeout)
• process.nextTick, setImmediate
• most database connections
• network connections
• Promises

同步回调示例:

• EventEmitter(取决于事件何时触发)
• 数组迭代等方法forEach
• Array sort 比较器回调
• String replace 匹配回调

• EventEmitter (depends on when the event is fired)
• Array iteration methods like forEach
• Array sort comparator callbacks
• String replace match callbacks

另见所有的javascript回调都是异步的吗?如果不是，我怎么知道哪些是?(包括其他一些示例).

See also Are all javascript callbacks asynchronous? If not, how do I know which are? (including some other examples).

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