Node.js Readfile with Javascript

Node.js is a popular Javascript runtime environment that is used for building scalable server-side applications. One of the most common tasks performed in any server-side application is working with files.

In this tutorial, we will look at how to use Node.js to read files using Javascript.

Reading a File with Node.js

To read a file using Node.js, we first need to require the built-in fs module. This module provides us with several methods for working with the file system, including fs.readFile() which we will use to read the file.

// Import the fs module
const fs = require('fs');

// Read the contents of a file using fs.readFile()
fs.readFile('/path/to/file', 'utf8', (err, data) => {
  if (err) throw err;
  console.log(data);
});

In the code above, we first import the fs module by requiring it using require('fs'). Next, we use the fs.readFile() method to read the contents of the file.

The fs.readFile() method takes three arguments:

• The file path (e.g. '/path/to/file')
• The encoding to use for the file (e.g. 'utf8'; if you leave this argument out, the data will be returned as a Buffer object)
• A callback function that is called with the contents of the file after it has been read

The callback function takes two arguments:

• An error (if one occurred while reading the file)
• The contents of the file (as a string if an encoding was specified, or as a Buffer object if no encoding was specified)

In the code above, we use a fat arrow (=>) to define the callback function. This is just a shorthand way of defining a function in Javascript.

If an error occurs while reading the file, we use throw err to throw an exception and stop the program from continuing. Otherwise, we log the contents of the file to the console using console.log(data).

Conclusion

Reading files is a common task in any server-side application. With Node.js, we can use the built-in fs module to read files using Javascript. In this tutorial, we looked at how to use the fs.readFile() method to read the contents of a file and the basics of callbacks.

Happy coding!