How to stop the camera stream from opening right away after DBR-JS demo is loaded? How to enable the camera on the click of a button?

let startScanBtn = document.getElementById("StartScanning"); // double check the ID of the button
startScanBtn.addEventListener("click", async function () {
  let scanner = await Dynamsoft.DBR.BarcodeScanner.createInstance();
  scanner.onFrameRead = (results) => {
    console.log(results);
  };
  scanner.onUniqueRead = (txt, result) => {
    alert(txt);
  };
  await scanner.show();
});