detecting if flash plugin is installed

gistfile1.js

var _flash_installed = ((typeof navigator.plugins != "undefined" && typeof navigator.plugins["Shockwave Flash"] == "object") || (window.ActiveXObject && (new ActiveXObject("ShockwaveFlash.ShockwaveFlash")) != false));

do u get the error in IE on a normal page or just inside devtools?

I get it on the page. I just tested this in IE6 and IE8. I get the generic "Object doesn't support this property or method" error message.

In more recent versions of IE, you will get an error from new ActiveXObject("ShockwaveFlash.ShockwaveFlash"), so instead you can use a try/catch:
var ie_flash; try { ie_flash = (window.ActiveXObject && (new ActiveXObject("ShockwaveFlash.ShockwaveFlash")) != false) } catch(err) { ie_flash = false; } var _flash_installed = ((typeof navigator.plugins != "undefined" && typeof navigator.plugins["Shockwave Flash"] == "object") || ie_flash);

The test in SWFObject is not
if (window.ActiveXObject....)
but
if (typeof window.ActiveXObject !='undefined' .....)

If anyone is looking for @jdalton's link target, you can see its archived version here: http://web.archive.org/web/20100710000820/http://www.adobe.com/support/flash/publishexport/scriptingwithflash/scriptingwithflash_03.html

Also, this appears to be the most stable version I've encountered: https://code.google.com/p/doctype-mirror/wiki/ArticleDetectFlash#The_code

Don't use this code; it fails in IE8. If flash is uninstalled, IE8 fails with "Automation server can't create object" error thrown. If flash is installed, IE8 fails anyway with "Object doesn't support this property or method" which I've isolated to the usage of the != operator instead of !== which does work. Either way, this cannot be reduced to a simple expression because the error is being thrown. It must be rewritten with some try/catch logic.

Best version so far is a slightly modified version of chustedde's code but with an !== false check instead of != false:

var ie_flash; try { ie_flash = (window.ActiveXObject && (new ActiveXObject("ShockwaveFlash.ShockwaveFlash")) !== false) } catch(err) { ie_flash = false; } var _flash_installed = ((typeof navigator.plugins != "undefined" && typeof navigator.plugins["Shockwave Flash"] == "object") || ie_flash); _flash_installed;

The last _flash_installed; statement is to have the JS console report the final result. Without it, Chrome, for example, would report "undefined".

See my gist at https://gist.github.com/JamesDunne/174ebedbc9afaf2078a7

Am facing an issue with latest Firefox 55 (win64). navigator.plugins is not returning "Shockwave Flash" even though flash is installed.
Could anyone suggest how to resolved this.
Thanks,