Extract complex condition to computed prop

app/assets/javascripts/boards/components/board.js

@@ -53,6 +53,9 @@ export default Vue.extend({
       const { issuesSize } = this.list;
       return `${n__('%d issue', '%d issues', issuesSize)}`;
     },
+    isNewIssueShown() {
+      return this.list.type === 'backlog' || (!this.disabled && this.list.type !== 'closed');
+    }
   },
   watch: {
     filter: {

app/views/shared/boards/components/_board.html.haml

@@ -41,7 +41,7 @@
 
         %button.issue-count-badge-add-button.btn.btn-sm.btn-default.ml-1.has-tooltip.js-no-trigger-collapse{ type: "button",
           "@click" => "showNewIssueForm",
-          "v-if" => 'list.type == "backlog" || (!disabled && list.type !== "closed")',
+          "v-if" => "isNewIssueShown",
           "aria-label" => _("New issue"),
           "title" => _("New issue"),
           data: { placement: "top", container: "body" } }