From c03ea47e4ef88782a0f43b3157d7712a03c44698 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 21 May 2025 15:09:21 -0400
Subject: [PATCH] chore: simplify `<pre>` cleaning (#15980)

---
 .changeset/fifty-llamas-know.md                 |  5 +++++
 .../src/compiler/phases/3-transform/utils.js    | 17 +++++------------
 2 files changed, 10 insertions(+), 12 deletions(-)
 create mode 100644 .changeset/fifty-llamas-know.md

diff --git a/.changeset/fifty-llamas-know.md b/.changeset/fifty-llamas-know.md
new file mode 100644
index 0000000000..f11c975f3d
--- /dev/null
+++ b/.changeset/fifty-llamas-know.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: simplify `<pre>` cleaning
diff --git a/packages/svelte/src/compiler/phases/3-transform/utils.js b/packages/svelte/src/compiler/phases/3-transform/utils.js
index 5aa40c8abb..5803c04947 100644
--- a/packages/svelte/src/compiler/phases/3-transform/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/utils.js
@@ -271,19 +271,12 @@ export function clean_nodes(
 
 	var first = trimmed[0];
 
-	// initial newline inside a `<pre>` is disregarded, if not followed by another newline
+	// if first text node inside a <pre> is a single newline, discard it, because otherwise
+	// the browser will do it for us which could break hydration
 	if (parent.type === 'RegularElement' && parent.name === 'pre' && first?.type === 'Text') {
-		const text = first.data.replace(regex_starts_with_newline, '');
-		if (text !== first.data) {
-			const tmp = text.replace(regex_starts_with_newline, '');
-			if (text === tmp) {
-				first.data = text;
-				first.raw = first.raw.replace(regex_starts_with_newline, '');
-				if (first.data === '') {
-					trimmed.shift();
-					first = trimmed[0];
-				}
-			}
+		if (first.data === '\n' || first.data === '\r\n') {
+			trimmed.shift();
+			first = trimmed[0];
 		}
 	}