test:

src/jensen.js

@@ -75,6 +75,7 @@ function Jensen(log) {
   this.onreceive = null;
 
   const RECV_BUFF_SIZE = 51200;
+  let worker = null;;
 
   const _check_conn_status = () => {
     if (device?.opened === false) {
@@ -145,6 +146,10 @@ function Jensen(log) {
       Logger.error('jensen', 'init', 'webusb not supported');
       return;
     }
+    if (window.worker) {
+      worker = new Worker('./utils/worker.js');
+      Worker.postMessage('Hello, World.');
+    }
     navigator.usb.onconnect = function (e) {
       self.tryconnect();
     };
@@ -294,6 +299,7 @@ function Jensen(log) {
     if (device)
       device.transferIn(2, RECV_BUFF_SIZE).then((r) => {
         Logger.save?.('jensen', 'tryReceive', r?.data);
+        worker.postMessage(r);
         receive(r);
       });
   };
@@ -701,6 +707,35 @@ Jensen.prototype.setTime = async function (time, seconds) {
   return this.send(new Command(SET_DEVICE_TIME).body(this.to_bcd(str)), seconds);
 };
 
+Jensen.prototype.streaming  = async function (filename, length, ondata, onprogress) {
+  if (typeof length != 'number') throw new Error('parameter `length` required');
+  if (length <= 0) throw new Error('parameter `length` must greater than zero');
+
+  Logger.info('jensen', 'streaming', `file download start. filename: ${filename}, length: ${length} `);
+
+  let fname = [];
+  for (let i = 0; i < filename.length; i++) fname.push(filename.charCodeAt(i));
+
+  let flen = 0;
+  let handler = (msg) => {
+    if (msg != null) {
+      flen += msg.body.length || msg.body.byteLength;
+      ondata(msg.body);
+      Logger.info('jensen', 'streaming length', `${length} ${flen}`);
+      if (flen >= length) {
+        Logger.info('jensen', 'streaming', 'file download finish.');
+        return 'OK';
+      }
+    } else {
+      Logger.info('jensen', 'streaming', 'file download fail.');
+      ondata('fail');
+    }
+  };
+  this.onreceive = onprogress;
+  Jensen.registerHandler(TRANSFER_FILE, handler);
+  this.send(new Command(TRANSFER_FILE).body(fname));
+};
+
 Jensen.prototype.getFile = async function (filename, length, ondata, onprogress) {
   if (typeof length != 'number') throw new Error('parameter `length` required');
   if (length <= 0) throw new Error('parameter `length` must greater than zero');