No longer emit trailing comma on object literals for ES3.

src/compiler/parser.ts

@@ -2106,14 +2106,20 @@ module ts {
         function parseObjectLiteral(): ObjectLiteral {
             var node = <ObjectLiteral>createNode(SyntaxKind.ObjectLiteral);
             parseExpected(SyntaxKind.OpenBraceToken);
-            if (scanner.hasPrecedingLineBreak()) node.flags |= NodeFlags.MultiLine;
-            node.properties = parseDelimitedList(ParsingContext.ObjectLiteralMembers, parseObjectLiteralMember, TrailingCommaBehavior.Preserve);
+            if (scanner.hasPrecedingLineBreak()) {
+                node.flags |= NodeFlags.MultiLine;
+            }
+
+            // ES3 itself does not accept a trailing comma in an object literal, however, we'd like to preserve it in ES5.
+            var trailingCommaBehavior = languageVersion === ScriptTarget.ES3 ? TrailingCommaBehavior.Allow : TrailingCommaBehavior.Preserve;
+
+            node.properties = parseDelimitedList(ParsingContext.ObjectLiteralMembers, parseObjectLiteralMember, trailingCommaBehavior);
             parseExpected(SyntaxKind.CloseBraceToken);
 
             var seen: Map<SymbolFlags> = {};
             var Property    = 1;
             var GetAccessor = 2;
-            var SetAccesor = 4;
+            var SetAccesor =  4;
             var GetOrSetAccessor = GetAccessor | SetAccesor;
             forEach(node.properties, (p: Declaration) => {
                 if (p.kind === SyntaxKind.OmittedExpression) {

tests/baselines/reference/assignmentCompatBug2.js

@@ -50,21 +50,21 @@ b3 = {
     g: function (s) {
         return 0;
     },
-    m: 0,
+    m: 0
 };
 b3 = {
     f: function (n) {
         return 0;
     },
     g: function (s) {
         return 0;
-    },
+    }
 };
 b3 = {
     f: function (n) {
         return 0;
     },
-    m: 0,
+    m: 0
 };
 b3 = {
     f: function (n) {
@@ -77,7 +77,7 @@ b3 = {
     n: 0,
     k: function (a) {
         return null;
-    },
+    }
 };
 b3 = {
     f: function (n) {
@@ -89,5 +89,5 @@ b3 = {
     n: 0,
     k: function (a) {
         return null;
-    },
+    }
 };

tests/baselines/reference/commentsOnObjectLiteral2.js

@@ -16,5 +16,5 @@ var Person = makeClass(
 var Person = makeClass({
     initialize: function (name) {
         this.name = name;
-    },
+    }
 });

tests/baselines/reference/convertKeywordsYes.js

@@ -380,7 +380,7 @@ var bigObject = {
     var: 0,
     void: 0,
     while: 0,
-    with: 0,
+    with: 0
 };
 var bigClass = (function () {
     function bigClass() {

tests/baselines/reference/declFileModuleAssignmentInObjectLiteralProperty.js

@@ -21,7 +21,7 @@ var m1;
 })(m1 || (m1 = {}));
 var d = {
     m1: { m: m1 },
-    m2: { c: m1.c },
+    m2: { c: m1.c }
 };
 
 

tests/baselines/reference/objectLitIndexerContextualType.js

@@ -26,14 +26,14 @@ y = {
 var x;
 var y;
 x = {
-    s: function (t) { return t * t; },
+    s: function (t) { return t * t; }
 };
 x = {
-    0: function (t) { return t * t; },
+    0: function (t) { return t * t; }
 };
 y = {
-    s: function (t) { return t * t; },
+    s: function (t) { return t * t; }
 };
 y = {
-    0: function (t) { return t * t; },
+    0: function (t) { return t * t; }
 };

tests/baselines/reference/objectLiteralParameterResolution.js

@@ -25,5 +25,5 @@ var s = $.extend({
     dataType: "json",
     converters: { "text json": "" },
     traditional: true,
-    timeout: 12,
+    timeout: 12
 }, "");

tests/baselines/reference/objectTypeWithStringNamedPropertyOfIllegalCharacters.js

@@ -77,7 +77,7 @@ var r4 = a["~!@#$%^&*()_+{}|:'<>?\/.,`"];
 var b = {
     "   ": 1,
     "a   b": "",
-    "~!@#$%^&*()_+{}|:'<>?\/.,`": 1,
+    "~!@#$%^&*()_+{}|:'<>?\/.,`": 1
 };
 var r = b["   "];
 var r2 = b["    "];

tests/baselines/reference/stringLiteralTypesInImplementationSignatures2.js

@@ -44,5 +44,5 @@ var b = {
     foo: function (x) {
     },
     foo: function (x) {
-    },
+    }
 };

tests/baselines/reference/thisInPropertyBoundDeclarations.js

@@ -101,13 +101,13 @@ var A = (function () {
         this.prop4 = {
             a: function () {
                 return this;
-            },
+            }
         };
         this.prop5 = function () {
             return {
                 a: function () {
                     return this;
-                },
+                }
             };
         };
     }

tests/baselines/reference/trailingCommasES3.js

@@ -0,0 +1,25 @@
+//// [trailingCommasES3.ts]
+
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2, };
+var o3 = { a: 1, };
+var o4 = {};
+
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];
+
+//// [trailingCommasES3.js]
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2 };
+var o3 = { a: 1 };
+var o4 = {};
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];

tests/baselines/reference/trailingCommasES5.js

@@ -0,0 +1,25 @@
+//// [trailingCommasES5.ts]
+
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2, };
+var o3 = { a: 1, };
+var o4 = {};
+
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];
+
+//// [trailingCommasES5.js]
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2,  };
+var o3 = { a: 1,  };
+var o4 = {};
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];

tests/cases/compiler/trailingCommasES3.ts

@@ -0,0 +1,13 @@
+// @target: es3
+
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2, };
+var o3 = { a: 1, };
+var o4 = {};
+
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];

tests/cases/compiler/trailingCommasES5.ts

@@ -0,0 +1,13 @@
+// @target: es5
+
+var o1 = { a: 1, b: 2 };
+var o2 = { a: 1, b: 2, };
+var o3 = { a: 1, };
+var o4 = {};
+
+var a1 = [1, 2];
+var a2 = [1, 2, ];
+var a3 = [1, ];
+var a4 = [];
+var a5 = [1, , ];
+var a6 = [, , ];