Add missing included code

js/tests/block-chain_test.js

@@ -1,3 +1,8 @@
+const hashCode = str =>
+  (
+    [...str].reduce((h, c) => (h = (h << 5) - h + c.charCodeAt(0)) & h, 0) >>> 0
+  ).toString(36)
+// /*/ // ⚡
 export const tests = []
 const t = (f) => tests.push(f)