Hi,

See this function in the following path, odoo/addons/point_of_sale/static/src/js/chrome.js

/** Print an overview of todays sales.
 *
 * By default this will print all sales of the day for current PoS config.
 */
print_sale_details: function () {
    var self = this;
    rpc.query({
        model: 'report.point_of_sale.report_saledetails',
        method: 'get_sale_details',
        args: [false, false, false, [this.pos.pos_session.id]],
    })
    .then(function(result){
        var env = {
            widget: new PosBaseWidget(self),
            company: self.pos.company,
            pos: self.pos,
            products: result.products,
            payments: result.payments,
            taxes: result.taxes,
            total_paid: result.total_paid,
            date: (new Date()).toLocaleString(),
        };
        var report = QWeb.render('SaleDetailsReport', env);
        self.pos.proxy.printer.print_receipt(report);
    });
},

Thanks