How to use the built-in module in Node.js
Most people do not understand the knowledge points of this article "how to use the built-in module in Node.js", so the editor summarizes the following, detailed content, clear steps, and has a certain reference value. I hope you can get something after reading this article. Let's take a look at this "how to use the built-in module in Node.js" article.
Built in module
Some chestnuts.
Node.js built-in module operation mechanism
Through Node.js source code analysis
The application layer code calls the Node.js module
The Node.js module calls the underlying C++ module through internalBinding
The built-in module of Node is stored in the lib folder
The built-in module calls methods at the internalBinding V8 level
InternalBinding is in the C++ code in the src directory
The C++ code defines some underlying methods, which are exported through the interface of V8 for call at the Node level.
Finally, the Node layer returns to the application layer
EventEmitter (Observer Mode)
In some cases, the data is not called through the Node.js source code, but directly notified to the Node.js code by the operating system to do something, such as EventEmitter
Chestnut process.stdin.on ("data", (e) = > {const playerAction = e.toString () .trim ();})
The principle of on events is implemented using Class: EventEmitter
EventEmitter can pass some changes that occur at the bottom, such as receiving a mouse event, to the application layer, so that developers can do the corresponding operations.
Event listener application scenario
Using observer mode to solve the problem of communication between multiple module objects
/ / index.jsconst EventEmitter = require ("events"). EventEmitter;class GeekTime extends EventEmitter {constructor () {super (); setInterval () = > {this.emit ("newLesson", {price: Math.random () * 100});}, 3000);} const geekTime = new GeekTime (); module.exports = geekTime;// buy.jsconst geekTime = require (". / index.js") GeekTime.addListener ("newLesson", (res) = > {console.log ("New lessons!", res.price); if (res.price < 80) {console.log ("Price is less than 80, buy!") ;})
Node.js Chestnut: EventEmitter
Browser Chestnut-addEventListener-removeEventListener
The distinction between Observer Mode and publish-subscribe Model
In the publish-subscribe model, the registration and trigger of events take place on a third-party platform independent of both parties. JS implementation-callback function observer mode: the publisher touches the subscriber directly. JS implementation-throwing an event
The above is about the content of this article on "how to use the built-in modules in Node.js". I believe we all have some understanding. I hope the content shared by the editor will be helpful to you. If you want to know more about the relevant knowledge, please pay attention to the industry information channel.
