Node JS fs.readFile() Method

The fs.readFile() method in Node.js is part of the fs (File System) module and is used to asynchronously read the contents of a file.

Here is a basic syntax:

const fs = require('fs');

fs.readFile(path, options, (err, data) => {
  if (err) {
    console.error('Error reading file:', err);
    return;
  }
  // The file content is in the `data` argument
  console.log('File content:', data.toString()); // converting buffer to string
});

Parameters:

1. path (string | Buffer | URL): The path to the file you want to read.
2. options (optional):
   • encoding (string | null): The character encoding to use (e.g., 'utf8'). If not provided, it will return a Buffer.
   • flag (string): A string flag to specify the behavior (e.g., 'r' for reading).
3. callback: A callback function that takes two arguments:
   • err: An error object (if an error occurs).
   • data: The content of the file (as a Buffer or a string depending on the encoding).

Example with Encoding:

fs.readFile('example.txt', 'utf8', (err, data) => {
  if (err) {
    console.error('Error reading file:', err);
    return;
  }
  console.log('File content:', data);
});

Important Points:

• The method is asynchronous, so it does not block the execution of the program while the file is being read.
• The callback is executed once the file reading operation is complete, passing the file content (or error if something went wrong).
• If no encoding is specified, the result will be a Buffer, which you can convert to a string (using .toString()).