i need to merge some pdf-files with nodejs and need to create a document outline, too.

current code is:

const merge = require('easy-pdf-merge');
merge(pdffiles, './Documentation.pdf', function(err) {
  if (err) {
    return console.log(err)
  }
  console.log('Success')
})

it merges the pdf files but now i need to create the pdf outline, how can i do this?