Reading a text file

JavaScript:
Reading a text file

How to:

Here’s how you go about reading a text file in current JavaScript:

Using Node.js with Promises (Async/Await):

const fs = require('fs').promises;

async function readFile(filePath) {
  try {
    const data = await fs.readFile(filePath, 'utf8');
    console.log(data);
  } catch (error) {
    console.error('Got an error trying to read the file:', error);
  }
}

readFile('example.txt');

Sample output (contents of example.txt):

Hello, this is a text file!

Using fetch API in the browser:

async function fetchTextFile(fileUrl) {
  try {
    const response = await fetch(fileUrl);
    const text = await response.text();
    console.log(text);
  } catch (error) {
    console.error('Oops, something went wrong fetching the file:', error);
  }
}

fetchTextFile('example.txt');

Deep Dive

Originally, reading files in JavaScript was mostly a server-side affair, dealt with by Node.js. As JS danced into browsers with HTML5, APIs like FileReader and fetch arrived, making client-side file reading possible without a sweat.

Alternatives? Oh, there are a few. Streams can handle big files without hogging memory. Workers prevent UI freeze-ups. Libraries make complex tasks easier. Each has its place.

Under the hood, file reading may involve buffer management, character encoding (UTF-8, etc.), and error handling. Be mindful of security, too; browsers restrict file access for good reasons.

JavaScript:Reading a text file

How to:

Deep Dive

See Also

JavaScript:
Reading a text file