proper slash handling in button.js

ui/static/ui/button.js

@@ -6,7 +6,7 @@ const count = document.getElementById("COUNT");
 button.addEventListener("click", event => {
     button.disabled = true;
     button.classList.add("is-loading");
-    fetch('/button', {
+    fetch('/button/', {
         method: 'POST',
         headers: {
             'Content-Type': 'application/json',

ui/urls.py

@@ -2,5 +2,5 @@ from django.urls import path
 from . import views
 
 urlpatterns = [
-    path('button', views.button, name = 'button'),
+    path('button/', views.button, name = 'button'),
 ]