app.js

// Requires
const {join} = require('path');
const moment = require('moment');
const pdf = require('html-pdf');
const {promisify} = require('util');
const read = promisify(require('fs').readFile);
const handlebars = require('handlebars');


// PDF Options
const pdf_options = {format: 'A4', quality: 300};

// GeneratePDF
async function generatePDF () {
    // Data we're going to pass to Handlebars
    const data = {
        mycompany: {
            name: 'GeeX',
            address: 'Street 1',
            city: 'Amsterdam',
            zipcode: '1000 AA'
        },
        customer: {},
        invoice_no: generateInvoiceNo(),
        date_created: moment().format('DD/MM/YYYY'),
        date_due: moment().add(14, 'days').format('DD/MM/YYYY')
    };

    // Add customer data
    data.customer = {
        org: 'Your Org',
        name: 'Foo Bar',
        email: 'mail@domain.com'
    };

    data.products = [
        {
            name: 'Database development',
            price: 2410.00
        },
        {
            name: 'Creating memes',
            price: 0.00
        },
        {
            name: 'Domain registration (1 year)',
            price: 9.95
        },
        {
            name: 'Integrating Mollie in e-commerce platform(Node.js)',
            price: 0.00
        },
        {
            name: 'Hosting (3 months)',
            price: 75
        }
    ];

    const total = data.products.map(product => product.price).reduce((a,b) => a + b , 0);

    data.exvat = (total - (total / 1.21)).toFixed(2);

    data.total = total.toFixed(2);

    data.products.forEach(product => product.price = product.price.toFixed(2));

    // Read source template
    const source = await read(join(`${__dirname}/template.html`), 'utf-8');

    // Convert to Handlebars template and add the data
    const template = handlebars.compile(source);
    const html = template(data);

    // Generate PDF and promisify the toFile function
    const p = pdf.create(html, pdf_options);
    p.toFile = promisify(p.toFile);

    // Saves the file to the File System as invoice.pdf in the current directory
    await p.toFile(`${join(__dirname, 'invoice.pdf')}`);

};

function generateInvoiceNo() {
    return moment().format('YYYYMMDD');
}

generatePDF();