


This article will take you through the operation of reading and writing files in Nodejs
How to operate files in
Node? The following article will talk about how to use Nodejs to read and write files. I hope it will be helpful to you!
# Manipulating files is a basic function of the server and one of the necessary capabilities for back-end development.
Operating files mainly includes reading and writing. These functions Nodejs have already provided corresponding methods. Just call it.
Create folder
Synchronization method
const fs = require('fs') fs.mkdirSync(`${__dirname}/雷猴`)
NodeJS
There is a file module called fs
. To operate on files, this module must be introduced first.
Use the fs.mkdirSync
method to create a folder. Just enter the name of the folder to be created.
__dirname
refers to the absolute path of the folder where the current file is located.
Asynchronous creation
const fs = require('fs') fs.mkdir(`${__dirname}/雷猴`, err => { if (err) { console.error(err) } })
Use the fs.mkdir
method to create asynchronously. The first parameter is also the folder name, and the second is Back to the function, there is a err
parameter in this function, which can return error information.
Delete files
After creating the folder, I originally wanted to talk about "delete the folder". However, since all the files in the folder must be cleared before deleting it, the usage of Deleting files will be discussed first.
There are two ways to delete files: synchronous and asynchronous.
Synchronization fs.unlinkSync
const fs = require('fs') fs.unlinkSync(`${__dirname}/test.txt`);
fs.unlinkSync
Input the path and file name of the file to be deleted to delete the specified file.
Asynchronous fs.unlink
const fs = require('fs') fs.unlink(`${__dirname}/test.txt`, err => { if (err) { console.error(err) } })
fs.unlink
The method has 2 parameters. The first parameter is the file path and file name. The second parameter is the callback function that monitors deletion failure.
Delete Folder
Before deleting a folder, clear all files in the target folder. Files can be deleted using fs.unlinkSync
or fs.unlink
.
Sync
const fs = require('fs') fs.rmdirSync(`${__dirname}/雷猴`)
Asynchronous
const fs = require('fs') fs.rmdir(`${__dirname}/雷猴`, err => { if (err) { console.error(err) } })
The usage is similar to deleting files. There are also synchronous and asynchronous methods for deleting folders. , accepts 2 parameters asynchronously, and the second parameter is also a callback for monitoring error reports.
Write data
const fs = require('fs') const content = ' 雷猴雷猴\n' const opt = { flag: 'a', // a:追加写入;w:覆盖写入 } fs.writeFile('test.txt', content, opt, (err) => { if (err) { console.error(err) } })
fs.writeFile
method can write content to a file. If the file does not exist, it will be automatically created.
fs.writeFile
Parameter description:
- First parameter: file name
- Second parameter: written content
- The third parameter: writing mode (append, overwrite, etc.)
- The fourth parameter: error message monitoring
Reading data
const fs = require('fs') fs.readFile('fileName', (err, data) => { if (err) { console.error(err) return } // data 是二进制类型,需要转换成字符串 console.log(data.toString()) })
Use the fs.readFile
method to read data. The first parameter is the file name; the second parameter is the callback, err
monitors error messages, data
is the data read back.
It should be noted that the data
read back is a binary type of data, which needs to be converted into data we can understand using the toString()
method.
Check whether the file exists
const fs = require('fs') const exist = fs.existsSync('fileName') console.log(exist)
Use the fs.existsSync
method to check whether the specified file exists, and return true# if it exists. ## ; Otherwise, return
false.
Summary
If you useNodeJS as the backend, you cannot escape the knowledge of reading and writing files. Its most common function can write logs, such as collecting error logs, etc.
nodejs tutorial!
The above is the detailed content of This article will take you through the operation of reading and writing files in Nodejs. For more information, please follow other related articles on the PHP Chinese website!

JavaScript runs in browsers and Node.js environments and relies on the JavaScript engine to parse and execute code. 1) Generate abstract syntax tree (AST) in the parsing stage; 2) convert AST into bytecode or machine code in the compilation stage; 3) execute the compiled code in the execution stage.

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SublimeText3 Chinese version
Chinese version, very easy to use

SublimeText3 Mac version
God-level code editing software (SublimeText3)

SublimeText3 Linux new version
SublimeText3 Linux latest version
