print-bluetooth.js

// From https://github.com/WebBluetoothCG/demos/blob/gh-pages/bluetooth-printer/index.html
var SERVICE = '000018f0-0000-1000-8000-00805f9b34fb';
var WRITE = '00002af1-0000-1000-8000-00805f9b34fb';

var DATA = ''
    + '\x1B' + '\x61' + '\x31'                                              // center align
    + '\x1D' + '\x21' + '\x11' + 'Hello\nBluetooth!\n\n'                    // double font size
    + '\x1D' + '\x21' + '\x00' + '... from your friends\nat https://qz.io'  // normal font size
    + '\n\n\n\n\n\n\n';                                                     // feed paper

var deviceHandle;
navigator.bluetooth.requestDevice({ filters: [{ services: [SERVICE]}] }).then(device => {
    console.log(device);
    deviceHandle = device;
    return device.gatt.connect()
}).then(server => {
    console.log(server);
    return server.getPrimaryService(SERVICE);
}).then(service => {
    console.log(service);
    return service.getCharacteristic(WRITE);
}).then(channel => {
    console.log(channel);
    return channel.writeValue(new TextEncoder("utf-8").encode(DATA));
}).catch(error => {
    console.error(error)
}).finally(() => {
    deviceHandle.gatt.disconnect();
});

I am having difficulty printing on a thermal printer model HM-A400

SecurityError: Origin is not allowed to access the service. Tip: Add the service UUID to 'optionalServices' in requestDevice() options. https://goo.gl/HxfxSQ

What is your origin? Is it a private address? Is it an HTTPS address? It's been a while since I've tried this code, but from what I recall Google is pretty picky about this (for example, they block access to their crypto libs when using HTTP).

There's also a good chance that the security model has changed and that the code has become outdated. If so, feel free to fork this example and link the fork in the comments.

Hey, is it possible to print an image? Like, i want to print receipt that include company's logo on the top of the receipt

Hey, is it possible to print an image? Like, i want to print receipt that include company's logo on the top of the receipt

@fathulhusnan Hi! Yes, however this will require converting the image from a raster/pixel format over to valid ESC/POS commands. There are several libraries that claim to support this. Here's one of them: https://github.com/NielsLeenheer/EscPosEncoder?tab=readme-ov-file#image

Thank you so much! It's help a lot!