How I Made a Free Automated PDF Invoice Maker for Batch Billing All My Contractors

(() => {
    // grab the invoice API exposed by gdoc.io on the window object
    const { store, invoice } = window.invoiceAPI;

    // expose batchInvoice globally so you can call it from the console
    window.batchInvoice = async (invoices) => {
        for (const inv of invoices) {

            // reset the form before filling in the next invoice
            invoice.new();

            // fill in all invoice fields via the store
            store.set({
                'inv.number': inv.number,
                'currency': inv.currency,
                'date.value': inv.date,
                'dueDate.value': inv.dueDate,
                'paymentTerms.value': inv.paymentTerms,
                'poNumber.value': inv.poNumber,
                'from.value': inv.from,
                'billTo.value': inv.billTo,
                'notes.value': inv.notes,
                'terms.value': inv.terms,

                // tax, discount and shipping are optional:
                // if you pass a value, the field gets enabled automatically
                'tax.enabled': inv.tax != null ? '1' : '0',
                'tax.value': inv.tax || 0,
                'discount.enabled': inv.discount != null ? '1' : '0',
                'discount.value': inv.discount || 0,
                'discount.mode': inv.discountMode || 'abs', // 'abs' for fixed amount, 'pct' for percent
                'shipping.enabled': inv.shipping != null ? '1' : '0',
                'shipping.value': inv.shipping || 0,
                'amountPaid.value': inv.amountPaid || 0,
            });

            // each line item needs a unique key — built from timestamp + random suffix
            inv.items.forEach(item => {
                const id = Date.now().toString(36) + Math.random().toString(36).slice(2, 6);
                store.set({
                    [`items.${id}.name`]: item.name,
                    [`items.${id}.qty`]: item.qty,
                    [`items.${id}.price`]: item.price,
                });
            });

            // save state, then trigger PDF download
            invoice.save();
            await invoice.pdf();
        }
        console.log(`✅ ${invoices.length} invoices generated`);
    };
    return '🌋 gdoc.io Invoice Volcano activated! Feed batchInvoice([...]) and watch it erupt';
})();

batchInvoice([
    {
        number: '001',            // invoice number
        currency: '$',            // currency symbol shown on the invoice
        date: '2026-04-11',       // invoice date (YYYY-MM-DD)
        dueDate: '2026-05-11',    // payment due date
        paymentTerms: 'Net 30',   // payment terms label
        poNumber: 'PO-2026-001',  // purchase order number (optional)
        from: 'Acme Corp\n100 Main St\nNew York, NY 10001',    // sender details, use \n for line breaks
        billTo: 'TechStart Inc\n456 Oak Ave\nBoston, MA 02101', // recipient details
        items: [
            // each item: service/product name, quantity, unit price
            { name: 'Frontend Development', qty: 40, price: 120 },
            { name: 'Backend API',          qty: 30, price: 150 },
        ],
        discount: 15,           // discount value
        discountMode: 'pct',    // 'pct' = percentage, 'abs' = fixed amount
        tax: 10,                // tax rate in percent
        amountPaid: 5000,       // amount already paid (shown as a deduction)
        notes: 'Wire: Bank of America\nAcc: 1234567890', // payment instructions or any notes
        terms: 'Late payments subject to 1.5% monthly interest', // terms and conditions
    },
    {
        number: '002',
        currency: '€',
        date: '2026-04-11',
        dueDate: '2026-06-11',
        paymentTerms: 'Net 60',
        from: 'Digital Studio GmbH\nBerlinstr. 42\nBerlin, 10115',
        billTo: 'MegaShop EU\n8 Rue de Rivoli\nParis, 75001',
        items: [
            { name: 'UI/UX Design',     qty: 20, price: 95 },
            { name: 'Brand Guidelines', qty: 1,  price: 2500 },
        ],
        discount: 400,          // fixed discount of €400
        discountMode: 'abs',
        tax: 19,
        shipping: 50,           // shipping cost (optional)
        notes: 'IBAN: DE89 3704 0044 0532 0130 00',
        terms: 'Payment within 60 days',
    },
]);