From de88d1fbb69f2ee6b3d58a5e7bbf5f74ef132a13 Mon Sep 17 00:00:00 2001
From: Jean-Yves Moyen <jym@siteimprove.com>
Date: Tue, 22 Oct 2024 11:47:08 +0200
Subject: [PATCH] Stop using node:perf_hooks (#1704)

---
 .changeset/strong-cougars-push.md    |  7 +++++
 packages/alfa-performance/src/now.ts | 39 +++++++++++++---------------
 2 files changed, 25 insertions(+), 21 deletions(-)
 create mode 100644 .changeset/strong-cougars-push.md

diff --git a/.changeset/strong-cougars-push.md b/.changeset/strong-cougars-push.md
new file mode 100644
index 0000000000..2c7a015f94
--- /dev/null
+++ b/.changeset/strong-cougars-push.md
@@ -0,0 +1,7 @@
+---
+"@siteimprove/alfa-performance": patch
+---
+
+**Changed:** `Performance.now()` does not try to use `node:perf_hooks` anymore.
+
+This created problem when trying to bundle `Performance` for browsers, where `node:` imports are not available.
diff --git a/packages/alfa-performance/src/now.ts b/packages/alfa-performance/src/now.ts
index 6bf2d4d5cc..205945092b 100644
--- a/packages/alfa-performance/src/now.ts
+++ b/packages/alfa-performance/src/now.ts
@@ -1,25 +1,22 @@
 /// <reference lib="dom" />
 
-import type { Thunk } from "@siteimprove/alfa-thunk";
-
-import perfHooks from "node:perf_hooks";
-
-export let now: Thunk<number>;
-
-/**
- * The continuations are needed to correctly handle the "this" bindings.
- * Eta-contracting breaks in node 19.0.0 and above. This may be linked to the
- * upgrade to V8 10.7.
+/*
+ * Performance measurement comes from different places in NodeJS and browser
+ * environments. The former uses node:perf_hooks, while the latter uses the
+ * global performance object. Trying to use the wrong one leads to at best
+ * undefined value, at worst compile errors at build time.
  *
- * Date.now actually works without the eta-expansion, keeping it for
- * consistency.
+ * It seems to not be that easy to polyfill between the two. While it is easy
+ * to test whether performance is defined, trying to import perf_hooks is enough
+ * to crash bundlers like Webpack.
+ *
+ * Therefore, we just ignore node:perf_hooks and defaults to the widely available
+ * Date.now() if the performance object is not available.
  */
-if (typeof performance !== "undefined") {
-  now = () => performance.now();
-} else {
-  try {
-    now = () => perfHooks.performance.now();
-  } catch {
-    now = () => Date.now();
-  }
-}
+
+import type { Thunk } from "@siteimprove/alfa-thunk";
+
+export const now: Thunk<number> =
+  typeof performance !== "undefined"
+    ? () => performance.now()
+    : () => Date.now();