caash.js

/**
   USB kick code for the posiflex 4000 series:
   - 120 bytes including the report id
   - all 0x00 with byte[1] and byte[2] the drawer number
   - the drawers can be assigned a number 0-7 (default is 7)
**/
function openDrawer(number)
{
   // Posiflex Cash Drawer
  var deviceInfo = {
      vendorId: '0x0d3a',
      productId: '0x0207',
      data: "",
  };

   // Drawer number 0-7 (7 is default)
   var drawer = String.fromCharCode(number);
   //                               ^-- Drawer number
   var prepend = [drawer, drawer];


   // Create 120 byte null-filled string (119 bytes data + 1 byte reportId)
   var data = prepend.join('') + Array(120 - (prepend.length + 1)).fill("\u0000").join('');
   //                                                          ^-- Report ID is appended by QZ Tray automatically


   // Connect to QZ Tray, claim, write, release
   qz.websocket.connect().then(function() {
      return qz.hid.claimDevice(deviceInfo.vendorId, deviceInfo.productId);
   }).then(function() {
      return createDataChain(qz.hid.sendData, deviceInfo, data, 32);
   }).catch(function(sendErr) {
      console.error(sendErr);
   }).then(function() {
       return qz.hid.releaseDevice(deviceInfo.vendorId, deviceInfo.productId);
   }).catch(function(releaseErr) {
      console.error(sendErr);
   });
}

function createDataChain(targetFunction, deviceInfo, data, chunkLength) {
  var chain = Promise.resolve();
  for (var i = 0; i < data.length; i += chunkLength) {
      
      //copy object
      let newInfo = {
          vendorId: deviceInfo.vendorId,
          productId: deviceInfo.productId,
          usagePage: deviceInfo.usagePage,
          serial: deviceInfo.serial,
          data: "",
          endpoint: deviceInfo.endpoint
      };

      newInfo.data = data.substring(i, Math.min(i + chunkLength, data.length));
      console.log(newInfo.data);
      chain = chain.then(()=>targetFunction(newInfo));
  }
  return chain;
}