Quick And Dirty URL Shortner On Any Site

First, I think this is a terrible idea and you should never do this. Second, I did this right here on this site. 

I wanted to add a URL shortener to my website so when people go davidron.com/something, the user will be redirected to some arbitrary location. I added the following to my 404 page:

<script language="javascript">
var key = window.location.href.split("/")[3];
var urls={
    'ssh':"http://sdf.org/ssh",
    'blog':"http://blog.davidron.com",
    'emacs':"http://ratamacu.freeshell.org/qe",
}

if(key){
    if(urls[key]){
        window.location.href=urls[key]
    }else{
        document.write("'"+key+"' not found :(");
    }
}
</script>

Now, I can go to davidron.com/ssh to open a terminal or davidron.com/emacs to download a qe binary.

This has several disadvantages:

• It's a complete abuse of the 404 page, which should't redirect anywhere.
• It's javascript, and a URL shortener should really use HTTP 3xx redirects.
• It's slow because you have to load and render the 404 page, show (part of) the 404 page to the user, run the script on the 404 page.
• Whatever security through obscurity there might be in a cryptic short URL is lost by the fact that I've published the entire database of URLS on my 404 page.

It also has a couple of advantages:

• It's stupid easy.
• It works.
• It's easy to edit right in the HTML.