Merge pull request #38 from sveltejs/escape-newlines

fix: escape newlines and escape characters when quoting strings

Author: Rich-Harris

.changeset/shiny-pianos-clean.md

@@ -0,0 +1,5 @@
+---
+'esrap': patch
+---
+
+fix: escape newlines when quoting strings

src/handlers.js

@@ -115,7 +115,26 @@ function prepend_comments(comments, state, newlines) {
  * @param {'\'' | '"'} char
  */
 function quote(string, char) {
-	return char + string.replaceAll(char, '\\' + char) + char;
+	let out = char;
+	let escaped = false;
+
+	for (const c of string) {
+		if (escaped) {
+			out += c;
+			escaped = false;
+		} else if (c === '\\') {
+			out += '\\\\';
+			escaped = true;
+		} else if (c === char) {
+			out += '\\' + c;
+		} else if (c === '\n') {
+			out += '\\n';
+		} else {
+			out += c;
+		}
+	}
+
+	return out + char;
 }
 
 const OPERATOR_PRECEDENCE = {

test/quotes.test.js

@@ -61,3 +61,35 @@ test('escape double quotes if present in string literal', () => {
 
 	expect(code).toMatchInlineSnapshot(`"const foo = "b\\"ar";"`);
 });
+
+test('escapes new lines', () => {
+	const ast = load('const str = "a\\nb"');
+	clean(ast);
+	const code = print(ast).code;
+
+	expect(code).toMatchInlineSnapshot(`"const str = 'a\\nb';"`);
+});
+
+test('escapes escape characters', () => {
+	const ast = load('const str = "a\\\\nb"');
+	clean(ast);
+	const code = print(ast).code;
+
+	expect(code).toMatchInlineSnapshot(`"const str = 'a\\\\nb';"`);
+});
+
+test('does not escape already-escaped single quotes', () => {
+	const ast = load(`const str = 'a\\'b'`);
+	clean(ast);
+	const code = print(ast).code;
+
+	expect(code).toMatchInlineSnapshot(`"const str = 'a\\'b';"`);
+});
+
+test('does not escape already-escaped double quotes', () => {
+	const ast = load('const str = "a\\"b"');
+	clean(ast);
+	const code = print(ast).code;
+
+	expect(code).toMatchInlineSnapshot(`"const str = 'a"b';"`);
+});