in javascript how can I detect if a browser will display or download a pdf?

Question

Hi.

Say i have

• a webpage with an iframe:
• an url pointing to a pdf document: http://www.example.com
• some javascript that will do iframe.src=pdfurl

• a button that will trigger such javascript

  • if the browser is going to display the pdf inline, the button will say "view pdf" and when clicked will make the iframe visible

  • otherwise it will say "download pdf"

I found a way to detect wether the pdf has been loaded in the iframe: reading iframe.contentDocument.contentType after onload has fired, but

• this won't allow me to display the correct button
• onload does not fire if the file is being downloaded

Thanks :)

Answer 1

You could send a HEAD request to that resource and check what Content-Type and Content-Disposition values are being sent back. Based on these information you could determine whether a browser would display or download that resource.

Answer 2

To tell the client's browser to download a response as a file, set the Content-Disposition HTTP header to 'attachment' in your response. This is no guarantee, but it's the proper method of telling the browser how to handle the content.