From 7cb71ac572495d5ebcff043201d57e5444476057 Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 06:45:18 +0200
Subject: [PATCH 1/7] fix: improve matching of script tag

---
 .changeset/hip-balloons-begin.md              |   5 +
 .../src/compiler/phases/1-parse/index.js      |  13 +-
 .../comment-before-script/input.svelte        |   4 +
 .../samples/comment-before-script/output.json | 132 ++++++++++++++++++
 4 files changed, 152 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/hip-balloons-begin.md
 create mode 100644 packages/svelte/tests/parser-modern/samples/comment-before-script/input.svelte
 create mode 100644 packages/svelte/tests/parser-modern/samples/comment-before-script/output.json

diff --git a/.changeset/hip-balloons-begin.md b/.changeset/hip-balloons-begin.md
new file mode 100644
index 000000000000..f5bbf77cf07c
--- /dev/null
+++ b/.changeset/hip-balloons-begin.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: improve matching of script tag
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 6b7642c251bd..41c0dd2757b5 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -11,7 +11,7 @@ import read_options from './read/options.js';
 const regex_position_indicator = / \(\d+:\d+\)$/;
 
 const regex_lang_attribute =
-	/<!--[^]*?-->|<script\s+(?:[^>]*|(?:[^=>'"/]+=(?:"[^"]*"|'[^']*'|[^>\s]+)\s+)*)lang=(["'])?([^"' >]+)\1[^>]*>/;
+	/<!--[^]*?-->|<script\s+(?:[^>]*|(?:[^=>'"/]+=(?:"[^"]*"|'[^']*'|[^>\s]+)\s+)*)lang=(["'])?([^"' >]+)\1[^>]*>/g;
 
 export class Parser {
 	/**
@@ -49,7 +49,16 @@ export class Parser {
 
 		this.template = template.trimRight();
 
-		this.ts = regex_lang_attribute.exec(template)?.[2] === 'ts';
+		const lang_matches = this.template.matchAll(regex_lang_attribute);
+
+		for(const match of lang_matches)
+		{
+			if(!match[0]?.startsWith('<!--'))
+			{
+				this.ts = match?.[2] === 'ts';
+				break;
+			}
+		}
 
 		this.root = {
 			css: null,
diff --git a/packages/svelte/tests/parser-modern/samples/comment-before-script/input.svelte b/packages/svelte/tests/parser-modern/samples/comment-before-script/input.svelte
new file mode 100644
index 000000000000..5086ed08bb7d
--- /dev/null
+++ b/packages/svelte/tests/parser-modern/samples/comment-before-script/input.svelte
@@ -0,0 +1,4 @@
+<!--should not error out-->
+<script lang="ts">
+	let count: number;
+</script>
diff --git a/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json b/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json
new file mode 100644
index 000000000000..d1505bfedebe
--- /dev/null
+++ b/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json
@@ -0,0 +1,132 @@
+{
+	"css": null,
+	"js": [],
+	"start": 0,
+	"end": 27,
+	"type": "Root",
+	"fragment": {
+		"type": "Fragment",
+		"nodes": [
+			{
+				"type": "Comment",
+				"start": 0,
+				"end": 27,
+				"data": "should not error out",
+				"ignores": []
+			},
+			{
+				"type": "Text",
+				"start": 27,
+				"end": 28,
+				"raw": "\n",
+				"data": "\n"
+			}
+		],
+		"transparent": false
+	},
+	"options": null,
+	"instance": {
+		"type": "Script",
+		"start": 28,
+		"end": 76,
+		"context": "default",
+		"content": {
+			"type": "Program",
+			"start": 46,
+			"end": 67,
+			"loc": {
+				"start": {
+					"line": 1,
+					"column": 0
+				},
+				"end": {
+					"line": 4,
+					"column": 0
+				}
+			},
+			"body": [
+				{
+					"type": "VariableDeclaration",
+					"start": 48,
+					"end": 66,
+					"loc": {
+						"start": {
+							"line": 3,
+							"column": 1
+						},
+						"end": {
+							"line": 3,
+							"column": 19
+						}
+					},
+					"declarations": [
+						{
+							"type": "VariableDeclarator",
+							"start": 52,
+							"end": 65,
+							"loc": {
+								"start": {
+									"line": 3,
+									"column": 5
+								},
+								"end": {
+									"line": 3,
+									"column": 18
+								}
+							},
+							"id": {
+								"type": "Identifier",
+								"start": 52,
+								"end": 18,
+								"loc": {
+									"start": {
+										"line": 3,
+										"column": 5
+									},
+									"end": {
+										"line": 3,
+										"column": 18
+									}
+								},
+								"name": "count",
+								"typeAnnotation": {
+									"type": "TSTypeAnnotation",
+									"start": 57,
+									"end": 65,
+									"loc": {
+										"start": {
+											"line": 3,
+											"column": 10
+										},
+										"end": {
+											"line": 3,
+											"column": 18
+										}
+									},
+									"typeAnnotation": {
+										"type": "TSNumberKeyword",
+										"start": 59,
+										"end": 65,
+										"loc": {
+											"start": {
+												"line": 3,
+												"column": 12
+											},
+											"end": {
+												"line": 3,
+												"column": 18
+											}
+										}
+									}
+								}
+							},
+							"init": null
+						}
+					],
+					"kind": "let"
+				}
+			],
+			"sourceType": "module"
+		}
+	}
+}
\ No newline at end of file

From 650bc3e54f75aac5fc2074df5ff568927b35068c Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 06:57:40 +0200
Subject: [PATCH 2/7] better

---
 packages/svelte/src/compiler/phases/1-parse/index.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 41c0dd2757b5..87e616d0a6f6 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -53,9 +53,9 @@ export class Parser {
 
 		for(const match of lang_matches)
 		{
-			if(!match[0]?.startsWith('<!--'))
+			if(match[0]?.[1] === 's') // ensure it starts with '<s' to match script tags
 			{
-				this.ts = match?.[2] === 'ts';
+				this.ts = match[2] === 'ts';
 				break;
 			}
 		}

From d3eb8da4a4697ecb0f41a5b0b2d6087259c30f85 Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 07:07:27 +0200
Subject: [PATCH 3/7] better desc

---
 .changeset/hip-balloons-begin.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/hip-balloons-begin.md b/.changeset/hip-balloons-begin.md
index f5bbf77cf07c..d59f7fd0bb7c 100644
--- a/.changeset/hip-balloons-begin.md
+++ b/.changeset/hip-balloons-begin.md
@@ -2,4 +2,4 @@
 'svelte': patch
 ---
 
-fix: improve matching of script tag
+fix: improve script `lang` attribute matching

From 851f57fbddd2f942de25467016cf441058de486d Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 07:13:56 +0200
Subject: [PATCH 4/7] prettier

---
 packages/svelte/src/compiler/phases/1-parse/index.js | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 87e616d0a6f6..233a8d161733 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -51,10 +51,9 @@ export class Parser {
 
 		const lang_matches = this.template.matchAll(regex_lang_attribute);
 
-		for(const match of lang_matches)
-		{
-			if(match[0]?.[1] === 's') // ensure it starts with '<s' to match script tags
-			{
+		for (const match of lang_matches) {
+			if (match[0]?.[1] === 's') {
+				// ensure it starts with '<s' to match script tags
 				this.ts = match[2] === 'ts';
 				break;
 			}

From 21b64ed2219c868120a377b1276faeda2bc54bb7 Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 07:31:53 +0200
Subject: [PATCH 5/7] f

---
 .../parser-modern/samples/comment-before-script/output.json     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json b/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json
index d1505bfedebe..d52a3752b4af 100644
--- a/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json
+++ b/packages/svelte/tests/parser-modern/samples/comment-before-script/output.json
@@ -129,4 +129,4 @@
 			"sourceType": "module"
 		}
 	}
-}
\ No newline at end of file
+}

From 3bcb337d9bf2f97ced7486359d02fd9bcba8a8d9 Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 09:03:14 +0200
Subject: [PATCH 6/7] faster

---
 .../svelte/src/compiler/phases/1-parse/index.js   | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 233a8d161733..f1ddec9d4912 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -49,15 +49,14 @@ export class Parser {
 
 		this.template = template.trimRight();
 
-		const lang_matches = this.template.matchAll(regex_lang_attribute);
+		let match_lang;
 
-		for (const match of lang_matches) {
-			if (match[0]?.[1] === 's') {
-				// ensure it starts with '<s' to match script tags
-				this.ts = match[2] === 'ts';
-				break;
-			}
-		}
+		do match_lang = regex_lang_attribute.exec(template);
+		while (match_lang && match_lang[0][1] !== 's'); // ensure it starts with '<s' to match script tags
+
+		regex_lang_attribute.lastIndex = 0; // need to reset index to pass tests — otherwise do not use global regex
+
+		this.ts = match_lang?.[2] === 'ts';
 
 		this.root = {
 			css: null,

From d1e0298736092b146e8384cedc4faf1c56a31c44 Mon Sep 17 00:00:00 2001
From: navorite <navorite@gmail.com>
Date: Mon, 1 Jan 2024 17:03:36 +0200
Subject: [PATCH 7/7] desc

---
 .changeset/hip-balloons-begin.md                     | 2 +-
 packages/svelte/src/compiler/phases/1-parse/index.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.changeset/hip-balloons-begin.md b/.changeset/hip-balloons-begin.md
index d59f7fd0bb7c..413b25406567 100644
--- a/.changeset/hip-balloons-begin.md
+++ b/.changeset/hip-balloons-begin.md
@@ -2,4 +2,4 @@
 'svelte': patch
 ---
 
-fix: improve script `lang` attribute matching
+fix: improve script `lang` attribute detection
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index f1ddec9d4912..e99e91d052b3 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -54,7 +54,7 @@ export class Parser {
 		do match_lang = regex_lang_attribute.exec(template);
 		while (match_lang && match_lang[0][1] !== 's'); // ensure it starts with '<s' to match script tags
 
-		regex_lang_attribute.lastIndex = 0; // need to reset index to pass tests — otherwise do not use global regex
+		regex_lang_attribute.lastIndex = 0; // reset matched index to pass tests - otherwise declare the regex inside the constructor
 
 		this.ts = match_lang?.[2] === 'ts';