This is a template I use for generating invoices. Putting this out there in the hope that it may be useful. You can use the template as long as you replace the colours, fonts, and imagery.
Put your personal and payment details in invoices/_you.json
and invoices/_payment.json
respectively.
npm install
npm run-script invoice
Open invoices/$DATE.json
in your favourite editor and add invoice and expense items.
node invoices.js
Open localhost:4000
in your favourite browser. Print your invoice or save it as a PDF.