Reading and writing files

A run sees the project's files in its working folder, read-only. A program may write files under /tmp; they are deleted when the run ends.

const fs = require('fs');

const rows = fs.readFileSync('data.csv', 'utf8').trim().split('\n').slice(1);
const names = rows.map((row) => row.split(',')[0]);
console.log(names);

fs.writeFileSync('/tmp/report.json', JSON.stringify({ count: names.length }));
console.log(JSON.parse(fs.readFileSync('/tmp/report.json', 'utf8')));

name,score
ada,90
alan,85

[ 'ada', 'alan' ]
{ count: 2 }

• Paths are relative to the project root: data/input.txt is the file shown in the explorer under data/.
• Writing next to your code fails with EROFS: read-only file system — write to /tmp instead.
• fs.promises.readFile is the async version, for use with await.