Delete random lines in a file

delete-random-lines.js

// Usage:
// node delete-random-lines.js some-file.txt

const fs = require('fs');

const lines = fs.readFileSync(process.argv[2], 'utf-8').split('\n');
const lineToDelete = Math.round(lines.length * 0.1);

for (let i = 0; i < lineToDelete; i++) {
  lines.splice(
    Math.floor(Math.random() * lines.length),
    1
  );
}

console.log(lines.join('\n'));