Summary of node.js commonly used fs file system (comprehensive)

This article brings you a summary of the commonly used fs file system in node.js (comprehensive). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

The fs file system module performs some read and write operations on system files and directories.

The methods in the module have asynchronous and synchronous versions. For example, the functions for reading file contents include asynchronous fs.readFile() and synchronous fs.readFileSync().

The last parameter of the asynchronous method function is the callback function, and the first parameter of the callback function contains error information (error).

It is recommended that you use asynchronous methods. Compared with synchronization, asynchronous methods have higher performance, faster speed, and no blocking.

Create file

fs.writeFile(filename,data,[options],function(err){})

If the file exists, write The input content will overwrite the old file content

filename (String) File name

data (String | Buffer) The content to be written can be string or buffer data.

options (Object) option array object, including

callback {Function} callback, passing an exception parameter err.

Append file

fs.appendFile(path,data,[options],function(err){})

name: File name

str: ​​Added field

encode: Set encoding

callback: Callback function, pass an exception parameter err

Read file

fs.readFile(path,options,function(err,data){})　

filename specific file storage Path address

[options] Specific option configuration, including data encoding method,

callback is a specific callback function for corresponding error capture and prompts.

Whether the file exists

fs.exists(path, function(exists){})

path The file path to be detected

callback callback

Note: The parameters of this callback are inconsistent with the parameters of other Node.js callbacks. It is not recommended to use fs.exists() to check whether the file exists before calling fs.open, fs.readFile(), fs.writeFile(). Doing so can cause a race condition because other processes may modify the file between calls. Instead, users should open/read/write files directly and handle errors when the file does not exist.

Delete file

fs.unlink(path,function(err){})

path - file path

callback - Callback function, err

Create folder

fs.mkdir(name,function(err){})

path - file path.

callback - callback function, err, create directory asynchronously. The completion callback has only one possible exception parameter.

Delete folder

fs.rmdir(path,function(err){})

path - file path.

callback - callback function, no parameters.

Read the folder

fs.readdir(path,function(err,files){})

path - file path.

callback - callback function, the callback function takes two parameters err, files, err is the error message, files is the file array list in the directory

Change the name

fs.rename(oldname,newname,function(err){})

Modify the file name to change the file storage path.

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