- Oct 02, 2018
- admin
- 0
Node.js File System:
To perform a file operation like creating, reading or writing a file in Node.js, Node.js File system module is a must to be included first.
● To include the File System module:
Syntax:
var variable_name = require(‘fs’);
Opening a file in Node.js:
To open a file in Node.js, fs.open() method is used.
Syntax:
fs.open(path, flags[, mode], callback)
Path: This parameter represents the path of the file to open.
Flags: This parameter specifies the flag that represents the mode of the file to open. The different values of flags are listed below:
Flags DESCRIPTION
| Flags | DESCRIPTION |
| r | Read only mode. Exception occurs if the file does not exist. |
| w | Write only mode. Either a new file is created, if it does not exist or it overwrites the existing file. |
| a | Write only mode. Either a new file is created, if it does not exist or it continues writing in the existing file. |
| r+ | Read Write mode. Exception occurs if the file does not exist. |
| w+ | Read Write mode. Either a new file is created, if it does not exist or it overwrites the existing file. |
| a+ | Read Write mode. Either a new file is created, if it does not exist or it continues writing in the existing file. |
| rs | Read only mode. Synchronous mode. |
| wx | Write only mode. Either a new file is created, if it does not exist or it fails if file exists. |
| ax | Write only mode. Either a new file is created, if it does not exist or it fails if file exists. |
| rs+ | Read Write mode. Synchronous mode. |
| wx+ | Read Write mode. Either a new file is created, if it does not exist or it fails if file exists. |
| ax+ | Read Write mode. Either a new file is created, if it does not exist or it fails if file exists. |
Mode: This parameter specifies the mode that can be either read, write or readwrite. The default value is 0666 which represents the readwrite mode.
Callback: When file open operation completes callback function is called with two arguments (err, fd).
Example:
var fs = require(‘fs’);
fs.open(‘example.txt’, ‘w+’, function (err, file)
{
if (err) throw err;
console.log(‘Successfully Opened!’);
});
OUTPUT:
Successfully Opened!
Reading a file in Node.js:
To read a file in Node.js, fs.readFile() method is used.
Writing a file in Node.js:
To write in a file in Node.js, fs.writeFile() method is used.
Appending a file in Node.js:
To append some contents to a file in Node.js, fs.appendFile() method is used.
Deleting a file in Node.js:
To delete a file in Node.js, fs.unlink() method is used.
Renaming a file in Node.js:
To rename an already existing file in Node.js, fs.rename() method is used.
