I will choose different style of detecting.
To detect whether javascript is enabled/disabled, i will write some little elements (perhaps div) and i will execute some javascript to remove such elements. Hence, when the javascript is disabled/doesn't exist, those elements will still be there saying that "Please activate your Javascript". On the other hand, those element(s) will be gone since javascript is already remove them. After all, it comes back to your website concept. Some website can't do anything when javascript is not exist/disabled and further they choose to redirect the request into another page (through tag). Some websites still can function but certain feature will not be available, and this concept leads to "warning" technique.
To detect whether cookie is enabled/disabled, just set a cookie using Javascript. In next request, you can check whether such cookie is set or not. If it's set, then both Javascript and Cookie is enabled. If it's not set, then Javascript or Cookie or both is disabled.
Good luck