问题
How can you detect if a browser supports NPAPI from JavaScript? Not all of them do, and whilst I could rely on the user-agent I'd much rather do it a more reliable way if one exists.
Unfortunately, I can't simply detect if my plug-in has loaded or not, as it may be that the plugin simply isn't installed yet on a supported browser.
Thanks.
回答1:
There is no JS API for this, but basically all desktop browsers except IE-/Trident-based ones and ChromeOS support NPAPI.
You can find out wether your plugin is installed by checking navigator.plugins.
回答2:
If you want to check whether java plugins are enabled or not in the browser then you should use the navigator.javaEnabled(). It will work in chrome.
来源：https://stackoverflow.com/questions/14838739/detecting-npapi-support-using-javascript