From ebd067054d747f7301774a4942a4a4618e40ebf3 Mon Sep 17 00:00:00 2001
From: Jakub Jankowski <jakubj@stoplight.io>
Date: Fri, 14 Aug 2020 21:22:05 +0200
Subject: [PATCH] feat: toc external link (#187)

---
 src/TableOfContents/index.tsx | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/TableOfContents/index.tsx b/src/TableOfContents/index.tsx
index 5cdece1e..01863054 100644
--- a/src/TableOfContents/index.tsx
+++ b/src/TableOfContents/index.tsx
@@ -140,7 +140,7 @@ function TableOfContentsInner<T extends TableOfContentsItem = TableOfContentsIte
         return (
           <RowComponent
             key={index}
-            item={item}
+            item={isExternalLink(item) ? { ...item, isExternalLink: true } : item}
             index={index}
             isExpanded={isExpanded}
             toggleExpanded={toggleExpandedFunctions[index]}
@@ -346,3 +346,11 @@ function findAncestorIndices(currentDepth: number, precedingContents: TableOfCon
     parentIndex,
   ];
 }
+
+function isExternalLink(item: TableOfContentsItem): boolean {
+  return isTableOfContentsLink(item) && item.to !== void 0 && /^(http|#|mailto)/.test(item.to);
+}
+
+function isTableOfContentsLink(item: TableOfContentsItem): item is ITableOfContentsLink {
+  return 'to' in item;
+}