From 5a65ca97464839fcd4ea59240b9910002fa64a82 Mon Sep 17 00:00:00 2001
From: Augustine Kim <augustinekim@google.com>
Date: Wed, 17 Aug 2022 18:09:35 -0700
Subject: [PATCH] [lit-html] Use existing `document` in Node build (#3223)

* Use existing document if present even in node mode
* This allows node build to run in DOM emulated node environments like node test runners
---
 .changeset/selfish-lobsters-cheat.md |  6 ++++++
 packages/lit-html/src/lit-html.ts    | 15 ++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)
 create mode 100644 .changeset/selfish-lobsters-cheat.md

diff --git a/.changeset/selfish-lobsters-cheat.md b/.changeset/selfish-lobsters-cheat.md
new file mode 100644
index 0000000000..ecb7584b19
--- /dev/null
+++ b/.changeset/selfish-lobsters-cheat.md
@@ -0,0 +1,6 @@
+---
+'lit-html': patch
+'lit': patch
+---
+
+Use existing `document` in Node build
diff --git a/packages/lit-html/src/lit-html.ts b/packages/lit-html/src/lit-html.ts
index 489910b855..185396a7ab 100644
--- a/packages/lit-html/src/lit-html.ts
+++ b/packages/lit-html/src/lit-html.ts
@@ -344,13 +344,14 @@ const markerMatch = '?' + marker;
 // syntax because it's slightly smaller, but parses as a comment node.
 const nodeMarker = `<${markerMatch}>`;
 
-const d = NODE_MODE
-  ? ({
-      createTreeWalker() {
-        return {};
-      },
-    } as unknown as Document)
-  : document;
+const d =
+  NODE_MODE && global.document === undefined
+    ? ({
+        createTreeWalker() {
+          return {};
+        },
+      } as unknown as Document)
+    : document;
 
 // Creates a dynamic marker. We never have to search for these in the DOM.
 const createMarker = (v = '') => d.createComment(v);