10-fs-synch.js

const {readFileSync, writeFileSync} = require('fs')

const first=readFileSync('./content/subfolder/first.txt','utf8');
const second=readFileSync('./content/subfolder/second.txt','utf8');

writeFileSync('./content/subfolder/result-sync.txt',`here is the result :${first},
 ${second}`,
 { flag:'a'})