printer.html


<html>
    <body>
        <textarea id="printContent"></textarea>
        <input type="submit" onclick="connectAndPrint()" value="Print"/>
        <P>Type text into box and click on submit button.
        <script>
        var device;
    
        function setup(device) {
            return device.open()
            .then(() => device.selectConfiguration(1))
            .then(() => device.claimInterface(0))
        }
    
        function print() {
            var string = document.getElementById("printContent").value + "\n";
            var encoder = new TextEncoder();
            var data = encoder.encode(string);
            device.transferOut(1, data)
            .catch(error => { console.log(error); })
        }
    
        function connectAndPrint() {
            if (device == null) {
                navigator.usb.requestDevice({ filters: [{ vendorId: 4070 }] })
                .then(selectedDevice => {
                    device = selectedDevice;
                    console.log(device);
                    return setup(device);
                })
                .then(() => print())
                .catch(error => { console.log(error); })
            }
            else
                print();
        }
    
        navigator.usb.getDevices()
        .then(devices => {
            if (devices.length > 0) {
                device = devices[0];
                return setup(device);
            }
        })
        .catch(error => { console.log(error); });
    
        </script>
    </body>
    </html>
    