Question

My task is to determine whether Java is installed and enabled on the browser the user came with.

I am using navigator.javaEnabled() method for this.

It works ok everywhere except for Chrome browser: it shows TRUE even if there is no Java plugin installed on Chrome at all.

Is this a bug or a feature?
How can I solve my task in Chrome?

Chrome 23, Windows.

Answer 1

This issue has been reported multiple times to the Chromium Project:

• http://code.google.com/p/chromium/issues/detail?id=36154
• http://code.google.com/p/chromium/issues/detail?id=108957

The former is open, the latter closed as WontFix.

There seems to be some disagreement in the community on what the value should return:

It’s not really clear what the correct behavior here is; it’s not part of the spec, and the description of the expected behavior in MDN is very specific to a preference that not only doesn’t exist in Chrome, but doesn’t even exist in Gecko any more (since it was replaced with the generic ability to enable and disable arbitrary plugins)

It looks like Chrome returns true based on these conditions:

Note that it specifically says it does not indicated whether Java is actually supported, only the value of a pref. So if the plugin is not installed, and therefore not explicitly disabled by the user, then according to those docs it should actually return true, not false. And we treat having a plugin installed but disabled exactly like not having it installed for web content purposes.

^{_{Emphasis mine}}

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So, the only solution that I can think of to detect if Java is running is to actually put an Applet on the page and see if you can interact with it from JavaScript.