NODE JS FILE SYSTEM MODULE

Date posted :02/05/2019

In this blog we are going to see about nodejs file modules and how to read create, update and delete the files.

INTRODUCTION:

Nodejs file system used to work with the file system on your computer.
File system module use the require() methods.

FILE SYSTEM MODULES

  • Read the file
  • create the file
  • update the file
  • delete the file
<html style="background: deepskyblue;">
<body>
<h1>Welcome to Nodejs</h1>
<p>This is my first file operation</p>
</body>
</html>

Create the html file for read the data. And save it as test.html

Read Files:

1)fs.readFile()

This function used to read the file.

var http = require('http');
var fs = require('fs');
http.createServer(function (req, res) {
  fs.readFile('test.html', function(err, data) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write(data);
    res.end();
  });
}).listen(8080);

Create the nodejs file and save it as testread.js.

Then run the following code in to your terminal. You can get the following out put.

>> node testread.js

CREATE A FILE:

1)fs.appendFile()

This method appends specified content to the end of the file.

var fs = require('fs');
fs.appendFile('mynewfile1.txt', 'Hello content!', function (err) {
   if (err) throw err;
   console.log('Saved!');
 });

2)fs.open()

This method takes a “flag” as the second arguments,w for write,the file is opened for writing.
If not exist empty file will create.

var fs = require('fs');

fs.open('mynewfile2.txt', 'w', function (err, file) {
  if (err) throw err;
  console.log('Saved!');
});

3)fs.writeFile()

The above method create the new file file1 and save the content “Hello content”.

var fs = require('fs');

fs.writeFile('mynewfile3.txt', 'Hello content!', function (err) {
  if (err) throw err;
  console.log('Saved!');
});

UPDATE FILES:

1)fs.appendFile()

This method append the text end of the file.

var fs = require('fs');

fs.appendFile('test', ' This is my text.', function (err) {
  if (err) throw err;
  console.log('Updated!');
});

2)fs.writeFile()

This method used to replace the content of the file.

var fs = require('fs');

fs.writeFile('mynewfile3.txt', 'This is my text', function (err) {
  if (err) throw err;
  console.log('Replaced!');
});

DELETE FILE:

1)fs.unlink()

This method used to delete the file.

var fs = require('fs');

fs.unlink('filename.txt', function (err) {
  if (err) throw err;
  console.log('File deleted!');
});

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