Thank you for your comment !
I’m a novice and I don’t know where to insert the command line [import pdfkit from “pdfkit”]. Do I have to create a .jsw file and start with that line … hmm, not so easy because I did it and did a copy past from the given exemple on their website and this is not good. I did something like that:
import pdfkit from “pdfkit”
PDFDocument = require ‘pdfkit’
// create a document and pipe to a blob
var doc = new PDFDocument();
var stream = doc.pipe(blobStream());
// draw some text
doc.fontSize(25)
.text(‘Here is some vector graphics…’, 100, 80);
…
doc.end();
If you have another tips… don’t hesitate 
Regards.