I'm almost finished with my website. The pages are completely made out of html,Css and Javascript. Now i would like to be able to change/add content really quickly and easily on the page. So of course i would need a CMS for that, something like Wordpress,drupal or joomla. But I want to use all of the html/css and javascript that i wrote. So my question is: is it possible to import Html/Css/JS to a CMS? I would like to use drupal, but any other good CMS will work too if this is possible.
Not Exactly.
most CMS are designed with MVC architecture (or with no architecture at all). Drupal is designed with PAC architecture. I actually prefer the latter.
What you should have done was designing your website on top of Drupal (or any other CMS).
Not all hope is lost yet :)
PAC architecture separates the Views from the Abstraction (or Model) more than other architectures (like MVC). This could make the process of implementing your design more easily. You should be able to take your web deisgn and 'push' the data from your CMS into it. I personally never worked with Drupal or Wordpress but theming your own site shouldn't be too hard. I guess you'll need to 'rebuild' your design with drupal's theming guidelines. Read the theming guides HERE.