sapper handles decoding now

routes/blog/[slug].json.js

@@ -8,7 +8,7 @@ posts.forEach(post => {
 export function get(req, res, next) {
 	// the `slug` parameter is available because
 	// this file is called [slug].json.js
-	const slug = decodeURIComponent(req.params.slug);
+	const { slug } = req.params;
 
 	if (lookup.has(slug)) {
 		res.writeHead(200, {