fix: avoid escape for jsx (#842)

crates/biome_formatter/src/token/string.rs

@@ -133,7 +133,11 @@ impl Quote {
 ///
 /// By default the formatter uses `\n` as a newline. The function replaces
 /// `\r\n` with `\n`,
-pub fn normalize_string(raw_content: &str, preferred_quote: Quote) -> Cow<str> {
+pub fn normalize_string(
+    raw_content: &str,
+    preferred_quote: Quote,
+    is_escape_preserved: bool,
+) -> Cow<str> {
     let alternate_quote = preferred_quote.other();
 
     // A string should be manipulated only if its raw content contains backslash or quotes
@@ -196,6 +200,9 @@ pub fn normalize_string(raw_content: &str, preferred_quote: Quote) -> Cow<str> {
                         // escape removed: "\a" => "a"
                         // So we ignore the current slash and we continue
                         // to the next iteration
+                        if is_escape_preserved {
+                            reduced_string.push(current_char);
+                        }
                         continue;
                     }
                 } else {

crates/biome_js_formatter/src/utils/string_utils.rs

@@ -309,12 +309,16 @@ impl<'token> LiteralStringNormaliser<'token> {
 
     fn normalize_string(&self, string_information: &StringInformation) -> Cow<'token, str> {
         let raw_content = self.raw_content();
+        let is_escape_preserved = matches!(self.token.token.kind(), JSX_STRING_LITERAL);
 
         if matches!(self.token.parent_kind, StringLiteralParentKind::Directive) {
             return Cow::Borrowed(raw_content);
         }
-
-        normalize_string(raw_content, string_information.preferred_quote.into())
+        normalize_string(
+            raw_content,
+            string_information.preferred_quote.into(),
+            is_escape_preserved,
+        )
     }
 
     fn raw_content(&self) -> &'token str {

crates/biome_js_formatter/tests/specs/jsx/attribute_escape.jsx

@@ -0,0 +1,15 @@
+const a = () => {
+	const a = "\test";
+	const b = "\\test";
+	const c = "\\\test";
+	const d = "\\\\test";
+
+	return (
+		<>
+			<input name="pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\\pin" type="text" pattern="\d{4,4}" required />
+		</>
+	);
+};

crates/biome_js_formatter/tests/specs/jsx/attribute_escape.jsx.snap

@@ -0,0 +1,68 @@
+---
+source: crates/biome_formatter_test/src/snapshot_builder.rs
+assertion_line: 212
+info: jsx/attribute_escape.jsx
+---
+
+# Input
+
+```jsx
+const a = () => {
+	const a = "\test";
+	const b = "\\test";
+	const c = "\\\test";
+	const d = "\\\\test";
+
+	return (
+		<>
+			<input name="pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\\pin" type="text" pattern="\d{4,4}" required />
+		</>
+	);
+};
+
+```
+
+
+=============================
+
+# Outputs
+
+## Output 1
+
+-----
+Indent style: Tab
+Indent width: 2
+Line ending: LF
+Line width: 80
+Quote style: Double Quotes
+JSX quote style: Double Quotes
+Quote properties: As needed
+Trailing comma: All
+Semicolons: Always
+Arrow parentheses: Always
+Bracket spacing: true
+Bracket same line: false
+-----
+
+```jsx
+const a = () => {
+	const a = "\test";
+	const b = "\\test";
+	const c = "\\\test";
+	const d = "\\\\test";
+
+	return (
+		<>
+			<input name="pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\pin" type="text" pattern="\d{4,4}" required />
+			<input name="\\\\pin" type="text" pattern="\d{4,4}" required />
+		</>
+	);
+};
+```
+
+

crates/biome_json_formatter/src/format_string.rs

@@ -16,7 +16,7 @@ impl Format<JsonFormatContext> for CleanedStringLiteralText<'_> {
         let content = self.token.text_trimmed();
         let raw_content = &content[1..content.len() - 1];
 
-        let text = match normalize_string(raw_content, Quote::Double) {
+        let text = match normalize_string(raw_content, Quote::Double, false) {
             Cow::Borrowed(_) => Cow::Borrowed(content),
             Cow::Owned(raw_content) => Cow::Owned(std::format!(
                 "{}{}{}",