How to determine if the user's browser can view PDF files

Question

What\'s the best way for determining whether the user\'s browser can view PDF files?

Ideally, it shouldn\'t matter on the browser or the operating system.

I

Answer 1

There are users that choose not to open PDF's in the browser and disable the plugin (this allows the file to be opened in the native application external of the browser window). It is better to let the user know that software is required to open something (whether it be PDF or not) than try to detect whether the plugin is available.

Another problem with detection is that what you need to look for changes from version to version (for example, see: "PDF.PdfCtrl.*" vs "AcroPDF.PDF.*" for the Adobe PDF viewer) and different browser implementations (the previously mentioned strings are used in IE for example, while Firefox uses a totally different manner of detection. Then we need to think of Opera and Safari and ???). Also, there are different vendors (think Foxit and Ghostscript, though I am not sure if they supply a plugin for the browser) where there may be differences in detecting the plugin.

For a script written in 2008 and some more information about the caveats see Detecting plugins in Internet Explorer (and a few hints for all the others).