Odczytywanie pliku tekstowego

JavaScript:
Odczytywanie pliku tekstowego

How to: (Jak to zrobić:)

Reading text files in JS depends on the environment: browser or Node.js. Here are both:

Browser:

// HTML5 File API for reading files in-browser
document.querySelector('input[type=file]').addEventListener('change', event => {
  const reader = new FileReader();
  
  reader.onload = function(e) {
    console.log('File content:', e.target.result);
  };

  reader.readAsText(event.target.files[0]);
});

Node.js:

const fs = require('fs');

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

Sample Output:

File content: Here is the text inside your file.

Deep Dive (Dogłębna analiza):

Historically, JS was client-side only, and file access was severely restricted for security reasons. Node.js introduced server-side JS, allowing file system access.

Alternatives:

fetch in browsers for remote files.
Streams in Node.js for big files to prevent memory overload.

Implementation:

The FileReader API in browsers works asynchronously.
Node.js fs.readFile reads the entire file into memory, but you can use fs.createReadStream for a more efficient approach.

JavaScript:Odczytywanie pliku tekstowego