From 1a66913dd4cfcfec6f79b89b218a0890c6005629 Mon Sep 17 00:00:00 2001
From: Jonathan Roebuck <jonathan.roebuck@bbc.co.uk>
Date: Wed, 2 Jun 2021 16:39:39 +0100
Subject: [PATCH] check for getEntriesByName in performance before calling

---
 src/getFCP.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/getFCP.ts b/src/getFCP.ts
index 65f0bd1a..c681bbe8 100644
--- a/src/getFCP.ts
+++ b/src/getFCP.ts
@@ -46,7 +46,7 @@ export const getFCP = (onReport: ReportHandler, reportAllChanges?: boolean) => {
 
   // TODO(philipwalton): remove the use of `fcpEntry` once this bug is fixed.
   // https://bugs.webkit.org/show_bug.cgi?id=225305
-  const fcpEntry = performance.getEntriesByName('first-contentful-paint')[0];
+  const fcpEntry = 'getEntriesByName' in performance ? performance.getEntriesByName('first-contentful-paint')[0] : null;
   const po = fcpEntry ? null : observe('paint', entryHandler);
 
   if (fcpEntry || po) {