How I fixed the trailing slash in Netlify rewrites

Netlify has this great feature that allows me to create a number of duplicate pages, by adding them into the _redirects file in the public root of the project (public/_redirects in Hugo, for example).

I use it to power some of my websites.

If I have a bunch of pages under content/original, by writing:

/copy/* /original/:splat  200

I can call the URL

/copy

and when I access https://mysite.com/copy I have the content stored inside https://mysite.com/original, and the URL does not change. It's not a redirect (despite the _redirects file name), it's a rewrite because I used the 200 code at the end. Had I used 301, that would have been a 301 redirect.

Anyway, the problem I stumbled upon is this: there's no way to automatically add the trailing slash at the end, so if you access /copy and /copy/, and you use relative URLs for images and links, without trailing slash URLs will lead to 404 and images will be broken.

I looked for a solution in my static site generator, to see if it could replicate redirects in another way, but in the end my solution was client side.

And very simple.

I added this JavaScript snippet at the bottom of my pages:

<script>
(function() {
  if (!location.href.endsWith('/')) {
    window.location = location.href + '/'
  }
}())
</script>

And the page now if there's no trailing slash will immediately reload with the slash appended at the end.

The process is so quick it's almost invisible to the user.