Updated tools, proper linting, build README

snippets/array-intersection.md

@@ -3,6 +3,6 @@
 Create a `Set` from `b`, then use `Array.filter()` on `a` to only keep values contained in `b`.
 
 ```js
-const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); }
+const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); };
 // intersection([1,2,3], [4,3,2]) -> [2,3]
 ```