function detectPlugin(substrs) {

    if (navigator.plugins) {

        for (var i = 0; i < navigator.plugins.length; i++) {

            var plugin = navigator.plugins[i];

            var haystack = plugin.name + plugin.description;

            var found = 0;

​

            for (var j = 0; j < substrs.length; j++) {

                if (haystack.indexOf(substrs[j]) != -1) {

                    found++;

                }

            }

            if (found == substrs.length) {

                return true;

            }

        }

    }

​

    return false;

}

​

if ( detectPlugin( [ "Shockwave", "Flash" ] ) ) alert( 'yay' );