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| File System |
File System
The Node.js File System module allows you to work with the file system on your computer.
Node.js has a set of built-in modules which you can use without any further installation. Similarly File System module contains a set of functions which are required to perform different operations on files such as read and write operation.
In order to to include a module, use the require() function with the name of the module.
const fs = require('fs');
Common use for the File System module:
- Read files
- Create files
- Update files
- Delete files
- Rename files
Reading a file
The fs.readFile() method is used to read file on your computer. It takes three arguments - filename, encoding and a call back function.
Node.js code to read file from your computer and return the content to the console.
const fs = require('fs');
fs.readFile('input.txt', 'utf-8', (err, data) => {
if (err) {
console.log(err);
}
else {
console.log("Content present in input.txt file : " + data.toString());
}
});
The above code reads a file input.txt from your computer and returns the content to the console.
Steps for execution :
- You should have Node.js installed in your computer.
- Create a file app.js and paste the above code.
- Create a file input.txt and write some content into it.
- Now open your console in the working directory and execute the command
node app.js.
Note : The input.txt file should be present in the same directory where your Node.js code file is present otherwise it will throw an error.
Writing in a file
The fs.writeFile() method takes three arguments - filename, content and a call back function.
Node.js code to write content into file.
const fs = require('fs');
fs.writeFile('output.txt', "New content added", (err, data) => {
if (err) {
console.log(err);
}
else {
console.log("The file is saved");
}
});
The above code creates a file output.txt and add content New content added to it.
Steps for execution :
- You should have Node.js installed in your computer.
- Create a file app.js and paste the above code.
- Now open your console in the working directory and execute the command
node app.js.
Note : If file does not exist then the fs.writeFile() method creates a file and writes the content into it. On the contrary if the file exists then it overwrites the content in the file.