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This article mainly explains "how to use the fs module and path module in node". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn how to use the fs module and path module in node.

Fs file system module

The fs module is officially provided by Node.js and is used to manipulate files. It provides a series of methods and properties to meet the needs of users for the operation of files.

The fs.readFile () method, which is used to read the contents of the specified file

The fs.writeFile () method, which is used to write to the specified file. If you want to use the fs module to manipulate the file in the JavaScript code, you need to import it in the following way:

Const fs = reuire ('fs')

Read the contents of the specified file

1. Syntax format of fs.readFile ()

Using the fs.readFile () method, you can read the contents of the specified file in the following syntax format:

Fs.readFile (path [, options], callback)

Parameter 1: a required parameter. You need to specify a string of file paths that indicates which path to read the corresponding file.

Parameter 2: an optional parameter indicating the encoding format in which the file is read.

Parameter 3: a required parameter. After the file is read, the read result is obtained through the callback function.

2. Sample code for fs.readFile ()

Reads the contents of the specified file in utf8 format and prints the values of err and data:

Const fs = require ('fs'); fs.readFile (' hello.txt', 'utf-8', (err, data) = > {/ / determine whether if (err) return console.log (err); console.log (data);})

Writes to the specified file

1. Syntax format of fs.writeFile ()

Using the fs.writeFile () method, you can write to a specified file in the following syntax format:

Fs.writeFile (file, data [, options], callback)

Parameter 1: a required parameter. You need to specify a string of file paths that represents the storage path of the file to be stored.

Parameter 2: a required parameter indicating what to write.

Parameter 3: optional parameter indicating the format in which the contents of the file are written. The default value is utf8.

Parameter 4: required parameter, callback function after the file is written.

2. Sample code for fs.writeFile ()

Const fs = require ('fs'); fs.writeFile ('. / hello.txt', 'hello node', (err) = > {/ / determine whether to write if (err) return console.log (err); console.log (' write successful');})

Read the names of all files in the specified directory

The syntax format of 1.fs.readdir ()

Using the fs.readdir () method, you can read the names of all files in the specified directory in the following syntax format:

Fs.readdir (path [, options], callback)

Parameter 1: a required parameter indicating the list of file names in which directory to read.

Parameter 2: optional parameter, in what format to read the file name in the directory, the default value is utf8.

Parameter 3: required parameter, read the callback function after completion.

Sample code for 2.fs.readdir ()

Through the fs.readdir () method, you can read the names of all files in the specified directory:

Const fs = require ('fs'); fs.readdir ('. /', (err, data) = > {/ / error handling if (err) return console.log (err); console.log (data);})

The problem of fs Module-path dynamic splicing

When using the fs module to manipulate files, if the operation path provided is a relative path that begins with. / or.. /, it is easy to cause the problem of path dynamic splicing errors. This is because at run time, the code dynamically splices the full path of the manipulated file to the directory where the node command was executed.

Solution: when using the fs module to manipulate files, directly provide absolute paths, do not provide relative paths at the beginning of. / or.. /, so as to prevent the problem of dynamic stitching of paths.

Note: use _ _ dirname to get the absolute path where the current file is located

Const fs = require ('fs'); / / stitching the absolute path of the file to read let filepath = _ _ dirname +' / hello.txt' fs.readFile (filepath, 'utf-8', (err, data) = > {/ / determine whether if (err) return console.log (err); console.log (data);}); path path module

The path module is officially provided by Node.js to handle paths. It provides a series of methods and properties to meet the path processing needs of users.

Path.join () method, which is used to concatenate multiple path fragments into a complete path string

The path.basename () method, which is used to parse the file name from the path string

If you want to use the path module to process the path in your JavaScript code, you need to import it in the following way:

Const path = require ('path')

Path splicing

The syntax format of path.join ()

Using the path.join () method, you can concatenate multiple path fragments into complete path strings in the following syntax format:

Path.join ([... paths])

Using the path.join () method, you can splice multiple path fragments into a complete path string:

Const path = require ('path'); console.log (path.join (' axed, 'baked,' c')); / / a/b/c console.log (path.join ('axed,' / btapped,'c')); / / a/b/c console.log (path.join ('averse,' / bAccord, 'croup,' index.html') / / a/b/c/index.html console.log (path.join ('averse,' baked,'.. / index.html')); / / a/c/index.html console.log (_ _ dirname); / / the global variable that comes with node, indicating the absolute path of the current js file / / the absolute path of the stitching result .txt (path.join (_ _ dirname, 'grade .txt')) / /-the most commonly used

Get the file name in the path

The syntax format of 1.path.basename ()

Using the path.basename () method, you can get the last part of the path, which is often used to get the file name in the path. The syntax format is as follows:

Path.basename (path [, ext])

Required parameter for path, which represents a string of paths

Ext optional parameter, indicating the optional file extension

Return: represents the last part of the path

Code example for 2.path.basename ()

Using the path.basename () method, you can get the name part of the file from a file path:

/ / find the file name console.log (path.basename ('index.html')); / / index.html console.log (path.basename (' a _

Get the file extension in the path

The syntax format of 1.path.extname ()

Using the path.extname () method, you can get the extension part of the path in the following syntax format:

Path.extname (path)

Required parameter for path, which represents a string of paths

Return: returns the resulting extended name string

Using the path.extname () method, you can get the extension part of the path

/ / find the character console.log (path.extname ('index.html')) followed by the last dot in the string; / / .html console.log (path.extname (' a.b.c.d.html')); / / .html console.log (path.extname ('asdfas/asdfa/a.b.c.d.html')); / / .html console.log (path.extname (' adf.adsf')) / / .adsf at this point, I believe you have a deeper understanding of "how to use the fs module and path module in node". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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