Ionic QR scanner

Once you’ve run the command you can just access the plugin directly, no need to import it or anything like that (you have to be running on a device though). So as it says in the docs:

   cordova.plugins.barcodeScanner.scan(
      function (result) {
          alert("We got a barcode\n" +
                "Result: " + result.text + "\n" +
                "Format: " + result.format + "\n" +
                "Cancelled: " + result.cancelled);
      }, 
      function (error) {
          alert("Scanning failed: " + error);
      }
   );

that will work anywhere in your code, or if you want to ES6 it up a bit:

   cordova.plugins.barcodeScanner.scan(
      (result) => {
          alert("We got a barcode\n" +
                "Result: " + result.text + "\n" +
                "Format: " + result.format + "\n" +
                "Cancelled: " + result.cancelled);
      }, 
      (error) => {
          alert("Scanning failed: " + error);
      }
   );