An article to talk about the reading and writing operations of node files

This article will talk about the fs file system module and introduce the file reading and writing operations innode. I hope it will be helpful to everyone!

fs file system module

##What is fs file system module

nodejs video tutorial,Programming teaching]

fs.readFile(): used for reading Get the file content of the specified file
• fs.writeFile(): used to write content to the specified file

const fs = require('fs');

Read the contents of the specified file

fs.readFile() Syntax:
• fs.readFile(path[,options],callback)
Parameters:
• path: required parameter, string format, indicating the path of the file
  • options:
  • OptionalParameters, indicating the encoding format to read the file
  Callback: Required parameter: After the file reading is completed, return to reading through this callback function The result (failure: failure information; success: read result)

test. txtdocument, and the content inside is:12341234

// 引入fs模块 const fs = require('fs'); // 读取文件 fs.readFile('./test.txt','utf-8',function(err,data){ console.log(err);// null console.log(data);// 12341234 })

• The first parameter represents the parameter that failed to read. At this time, we read successfully here. So the result is null

• The second parameter represents the result after successful reading. Here we read the content of the file, so the output is the content of the file.

Write content to the specified file

fs.writeFile() syntax:
• fs.writeFile(file,data [,options],callback);
Parameters:
• Parameter 1: Required parameter, string format, indicating the path of the file
  Parameter 2: Required Select parameters, indicating the content to be written
  Parameter 3:
  • OptionalParameter, indicating the encoding format to write the content in
  Parameter 4: Required parameter, file writing After entering the callback function

const fs = require('fs'); fs.writeFile('text.txt', '海绵宝宝', 'utf-8', function(err) { console.log(err);// null })

nullwill be output. Is that right? Does it mean that the writing has been successful?

text.txtfile has been generated. Open it and find that theSpongeBob SquarePants# we just wrote is official. ##.So if we execute the code again and only the written content changes, what will be the result?

fs.writeFile('text.txt', '派大星', 'utf-8', function(err) { console.log(err);// null })

At this time, we open the

file again and find that the content inside becomesPat Star, which means usingwirteFile()will overwrite the original content of the file.At this time, we can also judge whether the file is written successfully based on the value returned by the parameter of the write file callback function: if null is returned, it means the file is written successfully; otherwise, the writing fails.

EndThrough the fs module of

, we can read and write files Come on, this article is my study notes for learning node.js. If there are any shortcomings, I hope the experts can give me advice.For more node-related knowledge, please visit:

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