Question: In a Web application, is it possible to force a PDF file to be printed on the client? If the browser is configured to open the PDF inside the window, I guess that calling window.print() will work, but some browsers (like mine) are configured to open the PDF externally.

Answer: 
you can use the simple amazing library **printjs** "<http://printjs.crabbly.com>"
it takes PDF file and print it without showing print dialog if you need ,
a simple way to do it below :

```html
 <button type="button" onclick="printJS('docs/printjs.pdf')">
    Print PDF
 </button>
```
Do you mean that you want to force the file to be sent to a printer? Are you thinking of the Law of Unintended Consequences -- the user's device isn't connected to a printer? Could be a BlackBerry, could be a laptop on wi-fi. What if the user doesn't want it to go to the default printer?