open every file in a specific folder than open all of them and write "Coded by Inventex" to the first line as a comment

Script
function injectMyName(folder) {
  fs.readdir(folder, function(err, files) {
    files.forEach(function(file) {
      fs.readFile(file, fileContent => {
        fs.writeFile(file, `// Coded by Inventex\n\n${fileContent}`)
      }) 
    })
  })
}