Fix #19625

src/vs/base/common/json.ts

@@ -817,6 +817,7 @@ export function getLocation(text: string, position: number): Location {
 
 export interface ParseOptions {
 	disallowComments?: boolean;
+	allowTrailingComma?: boolean;
 }
 
 /**
@@ -1005,6 +1006,7 @@ export function visit(text: string, visitor: JSONVisitor, options?: ParseOptions
 		onError = toOneArgVisit(visitor.onError);
 
 	let disallowComments = options && options.disallowComments;
+	let allowTrailingComma = options && options.allowTrailingComma;
 	function scanNext(): SyntaxKind {
 		while (true) {
 			let token = _scanner.scan();
@@ -1116,6 +1118,9 @@ export function visit(text: string, visitor: JSONVisitor, options?: ParseOptions
 				}
 				onSeparator(',');
 				scanNext(); // consume comma
+				if (_scanner.getToken() === SyntaxKind.CloseBraceToken && allowTrailingComma) {
+					break;
+				}
 			} else if (needsComma) {
 				handleError(ParseErrorCode.CommaExpected, [], []);
 			}

src/vs/base/test/common/json.test.ts

@@ -234,6 +234,17 @@ suite('JSON', () => {
 		assertInvalidParse('{ "foo": /*comment*/ true }', { foo: true }, options);
 	});
 
+	test('parse: trailing comma', () => {
+		let options = { allowTrailingComma: true };
+		assertValidParse('{ "hello": [], }', { hello: [] }, options);
+		assertValidParse('{ "hello": [] }', { hello: [] }, options);
+		assertValidParse('{ "hello": [], "world": {}, }', { hello: [], world: {} }, options);
+		assertValidParse('{ "hello": [], "world": {} }', { hello: [], world: {} }, options);
+
+		assertInvalidParse('{ "hello": [], }', { hello: [] });
+		assertInvalidParse('{ "hello": [], "world": {}, }', { hello: [], world: {} });
+	});
+
 	test('location: properties', () => {
 		assertLocation('|{ "foo": "bar" }', [], void 0, false);
 		assertLocation('{| "foo": "bar" }', [], void 0, true);

src/vs/workbench/services/configuration/node/configurationEditingService.ts

@@ -233,7 +233,7 @@ export class ConfigurationEditingService implements IConfigurationEditingService
 
 				let error = void 0;
 				const parseErrors: json.ParseError[] = [];
-				json.parse(content, parseErrors);
+				json.parse(content, parseErrors, { allowTrailingComma: true });
 				if (!options.writeToBuffer && parseErrors.length > 0) {
 					error = ConfigurationEditingErrorCode.ERROR_INVALID_CONFIGURATION;
 				}