


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!

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