Minification: Create local variable for prototype during class declaration

src/compiler/transformers/es2015.ts

@@ -1578,21 +1578,28 @@ namespace ts {
          * @param node The ClassExpression or ClassDeclaration node.
          */
         function addClassMembers(statements: Statement[], node: ClassExpression | ClassDeclaration): void {
+            let prototypeName: Identifier;
             for (const member of node.members) {
                 switch (member.kind) {
                     case SyntaxKind.SemicolonClassElement:
                         statements.push(transformSemicolonClassElementToStatement(<SemicolonClassElement>member));
                         break;
 
                     case SyntaxKind.MethodDeclaration:
-                        statements.push(transformClassMethodDeclarationToStatement(getClassMemberPrefix(node, member), <MethodDeclaration>member, node));
+                        if (!prototypeName && !hasModifier(member, ModifierFlags.Static)) {
+                            prototypeName = addPrototypeDeclaration(statements, node);
+                        }
+                        statements.push(transformClassMethodDeclarationToStatement(getClassMemberPrefix(node, member, prototypeName), <MethodDeclaration>member, node));
                         break;
 
                     case SyntaxKind.GetAccessor:
                     case SyntaxKind.SetAccessor:
+                        if (!prototypeName && !hasModifier(member, ModifierFlags.Static)) {
+                            prototypeName = addPrototypeDeclaration(statements, node);
+                        }
                         const accessors = getAllAccessorDeclarations(node.members, <AccessorDeclaration>member);
                         if (member === accessors.firstAccessor) {
-                            statements.push(transformAccessorsToStatement(getClassMemberPrefix(node, member), accessors, node));
+                            statements.push(transformAccessorsToStatement(getClassMemberPrefix(node, member, prototypeName), accessors, node));
                         }
 
                         break;
@@ -1608,6 +1615,23 @@ namespace ts {
             }
         }
 
+        /**
+         * Adds a statement to the class body function declaring a local variable for the class prototype.
+         *
+         * @param statements The statements for the class body function.
+         * @param node The ClassExpression or ClassDeclaration node.
+         */
+        function addPrototypeDeclaration(statements: Statement[], node: ClassExpression | ClassDeclaration): Identifier {
+            const prototypeName: Identifier = createUniqueName("proto");
+            statements.push(createVariableStatement(/* modifiers */ undefined, [
+                createVariableDeclaration(
+                    prototypeName,
+                    /* type */ undefined,
+                    createPropertyAccess(getInternalName(node), "prototype"))
+            ]));
+            return prototypeName;
+        }
+
         /**
          * Transforms a SemicolonClassElement into a statement for a class body function.
          *
@@ -4040,10 +4064,10 @@ namespace ts {
             return node;
         }
 
-        function getClassMemberPrefix(node: ClassExpression | ClassDeclaration, member: ClassElement) {
+        function getClassMemberPrefix(node: ClassExpression | ClassDeclaration, member: ClassElement, prototypeAccessor: Identifier) {
             return hasModifier(member, ModifierFlags.Static)
                 ? getInternalName(node)
-                : createPropertyAccess(getInternalName(node), "prototype");
+                : prototypeAccessor;
         }
 
         function hasSynthesizedDefaultSuperCall(constructor: ConstructorDeclaration, hasExtendsClause: boolean) {

tests/baselines/reference/2dArrays.js

@@ -29,7 +29,8 @@ var Ship = (function () {
 var Board = (function () {
     function Board() {
     }
-    Board.prototype.allShipsSunk = function () {
+    var proto_1 = Board.prototype;
+    proto_1.allShipsSunk = function () {
         return this.ships.every(function (val) { return val.isSunk; });
     };
     return Board;

tests/baselines/reference/ClassDeclaration11.js

@@ -8,6 +8,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype.foo = function () { };
+    var proto_1 = C.prototype;
+    proto_1.foo = function () { };
     return C;
 }());

tests/baselines/reference/ClassDeclaration13.js

@@ -8,6 +8,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype.bar = function () { };
+    var proto_1 = C.prototype;
+    proto_1.bar = function () { };
     return C;
 }());

tests/baselines/reference/ClassDeclaration21.js

@@ -8,6 +8,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype[1] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[1] = function () { };
     return C;
 }());

tests/baselines/reference/ClassDeclaration22.js

@@ -8,6 +8,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype["bar"] = function () { };
+    var proto_1 = C.prototype;
+    proto_1["bar"] = function () { };
     return C;
 }());

tests/baselines/reference/ES5For-ofTypeCheck10.js

@@ -19,13 +19,14 @@ for (var v of new StringIterator) { }
 var StringIterator = (function () {
     function StringIterator() {
     }
-    StringIterator.prototype.next = function () {
+    var proto_1 = StringIterator.prototype;
+    proto_1.next = function () {
         return {
             done: true,
             value: ""
         };
     };
-    StringIterator.prototype[Symbol.iterator] = function () {
+    proto_1[Symbol.iterator] = function () {
         return this;
     };
     return StringIterator;

tests/baselines/reference/ES5SymbolProperty2.js

@@ -17,7 +17,8 @@ var M;
     var C = (function () {
         function C() {
         }
-        C.prototype[Symbol.iterator] = function () { };
+        var proto_1 = C.prototype;
+        proto_1[Symbol.iterator] = function () { };
         return C;
     }());
     M.C = C;

tests/baselines/reference/ES5SymbolProperty3.js

@@ -12,7 +12,8 @@ var Symbol;
 var C = (function () {
     function C() {
     }
-    C.prototype[Symbol.iterator] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[Symbol.iterator] = function () { };
     return C;
 }());
 (new C)[Symbol.iterator];

tests/baselines/reference/ES5SymbolProperty4.js

@@ -12,7 +12,8 @@ var Symbol;
 var C = (function () {
     function C() {
     }
-    C.prototype[Symbol.iterator] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[Symbol.iterator] = function () { };
     return C;
 }());
 (new C)[Symbol.iterator];

tests/baselines/reference/ES5SymbolProperty5.js

@@ -12,7 +12,8 @@ var Symbol;
 var C = (function () {
     function C() {
     }
-    C.prototype[Symbol.iterator] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[Symbol.iterator] = function () { };
     return C;
 }());
 (new C)[Symbol.iterator](0); // Should error

tests/baselines/reference/ES5SymbolProperty6.js

@@ -9,7 +9,8 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype[Symbol.iterator] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[Symbol.iterator] = function () { };
     return C;
 }());
 (new C)[Symbol.iterator];

tests/baselines/reference/ES5SymbolProperty7.js

@@ -12,7 +12,8 @@ var Symbol;
 var C = (function () {
     function C() {
     }
-    C.prototype[Symbol.iterator] = function () { };
+    var proto_1 = C.prototype;
+    proto_1[Symbol.iterator] = function () { };
     return C;
 }());
 (new C)[Symbol.iterator];

tests/baselines/reference/ExportClassWhichExtendsInterfaceWithInaccessibleType.js

@@ -27,7 +27,8 @@ var A;
             this.x = x;
             this.y = y;
         }
-        Point2d.prototype.fromOrigin = function (p) {
+        var proto_1 = Point2d.prototype;
+        proto_1.fromOrigin = function (p) {
             return 1;
         };
         return Point2d;

tests/baselines/reference/MemberAccessorDeclaration15.js

@@ -7,7 +7,8 @@ class C {
 var C = (function () {
     function C() {
     }
-    Object.defineProperty(C.prototype, "Foo", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "Foo", {
         set: function (a) { },
         enumerable: true,
         configurable: true

tests/baselines/reference/Protected4.js

@@ -7,6 +7,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype.m = function () { };
+    var proto_1 = C.prototype;
+    proto_1.m = function () { };
     return C;
 }());

tests/baselines/reference/Protected7.js

@@ -7,6 +7,7 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype.m = function () { };
+    var proto_1 = C.prototype;
+    proto_1.m = function () { };
     return C;
 }());

tests/baselines/reference/TwoInternalModulesThatMergeEachWithExportedAndNonExportedClassesOfTheSameName.js

@@ -54,7 +54,8 @@ var A;
     var Point = (function () {
         function Point() {
         }
-        Point.prototype.fromCarthesian = function (p) {
+        var proto_1 = Point.prototype;
+        proto_1.fromCarthesian = function (p) {
             return { x: p.x, y: p.y };
         };
         return Point;

tests/baselines/reference/abstractProperty.js

@@ -45,12 +45,13 @@ var C = (function (_super) {
         _this.ro = "readonly please";
         return _this;
     }
-    Object.defineProperty(C.prototype, "prop", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "prop", {
         get: function () { return "foo"; },
         set: function (v) { },
         enumerable: true,
         configurable: true
     });
-    C.prototype.m = function () { };
+    proto_1.m = function () { };
     return C;
 }(B));

tests/baselines/reference/abstractPropertyNegative.js

@@ -66,7 +66,8 @@ var C = (function (_super) {
         _this.ro = "readonly please";
         return _this;
     }
-    Object.defineProperty(C.prototype, "concreteWithNoBody", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "concreteWithNoBody", {
         get: function () { },
         enumerable: true,
         configurable: true
@@ -99,7 +100,8 @@ var WrongTypeAccessorImpl = (function (_super) {
     function WrongTypeAccessorImpl() {
         return _super !== null && _super.apply(this, arguments) || this;
     }
-    Object.defineProperty(WrongTypeAccessorImpl.prototype, "num", {
+    var proto_2 = WrongTypeAccessorImpl.prototype;
+    Object.defineProperty(proto_2, "num", {
         get: function () { return "nope, wrong"; },
         enumerable: true,
         configurable: true
@@ -118,13 +120,14 @@ var WrongTypeAccessorImpl2 = (function (_super) {
 var AbstractAccessorMismatch = (function () {
     function AbstractAccessorMismatch() {
     }
-    Object.defineProperty(AbstractAccessorMismatch.prototype, "p1", {
+    var proto_3 = AbstractAccessorMismatch.prototype;
+    Object.defineProperty(proto_3, "p1", {
         set: function (val) { },
         enumerable: true,
         configurable: true
     });
     ;
-    Object.defineProperty(AbstractAccessorMismatch.prototype, "p2", {
+    Object.defineProperty(proto_3, "p2", {
         get: function () { return "should work"; },
         enumerable: true,
         configurable: true

tests/baselines/reference/accessInstanceMemberFromStaticMethod01.js

@@ -11,7 +11,8 @@ class C {
 var C = (function () {
     function C() {
     }
-    C.prototype.bar = function () {
+    var proto_1 = C.prototype;
+    proto_1.bar = function () {
         var k = foo;
     };
     return C;

tests/baselines/reference/accessOverriddenBaseClassMember1.js

@@ -31,7 +31,8 @@ var Point = (function () {
         this.x = x;
         this.y = y;
     }
-    Point.prototype.toString = function () {
+    var proto_1 = Point.prototype;
+    proto_1.toString = function () {
         return "x=" + this.x + " y=" + this.y;
     };
     return Point;
@@ -43,7 +44,8 @@ var ColoredPoint = (function (_super) {
         _this.color = color;
         return _this;
     }
-    ColoredPoint.prototype.toString = function () {
+    var proto_2 = ColoredPoint.prototype;
+    proto_2.toString = function () {
         return _super.prototype.toString.call(this) + " color=" + this.color;
     };
     return ColoredPoint;

tests/baselines/reference/accessibilityModifiers.js

@@ -127,13 +127,14 @@ var D = (function () {
 var E = (function () {
     function E() {
     }
-    E.prototype.method = function () { };
-    Object.defineProperty(E.prototype, "getter", {
+    var proto_1 = E.prototype;
+    proto_1.method = function () { };
+    Object.defineProperty(proto_1, "getter", {
         get: function () { return 0; },
         enumerable: true,
         configurable: true
     });
-    Object.defineProperty(E.prototype, "setter", {
+    Object.defineProperty(proto_1, "setter", {
         set: function (a) { },
         enumerable: true,
         configurable: true

tests/baselines/reference/accessorParameterAccessibilityModifier.js

@@ -8,7 +8,8 @@ class C {
 var C = (function () {
     function C() {
     }
-    Object.defineProperty(C.prototype, "X", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "X", {
         set: function (v) { },
         enumerable: true,
         configurable: true

tests/baselines/reference/accessorWithES3.js

@@ -25,7 +25,8 @@ var y = {
 var C = (function () {
     function C() {
     }
-    Object.defineProperty(C.prototype, "x", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "x", {
         get: function () {
             return 1;
         },
@@ -37,7 +38,8 @@ var C = (function () {
 var D = (function () {
     function D() {
     }
-    Object.defineProperty(D.prototype, "x", {
+    var proto_2 = D.prototype;
+    Object.defineProperty(proto_2, "x", {
         set: function (v) {
         },
         enumerable: true,

tests/baselines/reference/accessorWithES5.js

@@ -22,7 +22,8 @@ var y = {
 var C = (function () {
     function C() {
     }
-    Object.defineProperty(C.prototype, "x", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "x", {
         get: function () {
             return 1;
         },
@@ -34,7 +35,8 @@ var C = (function () {
 var D = (function () {
     function D() {
     }
-    Object.defineProperty(D.prototype, "x", {
+    var proto_2 = D.prototype;
+    Object.defineProperty(proto_2, "x", {
         set: function (v) {
         },
         enumerable: true,

tests/baselines/reference/accessorWithInitializer.js

@@ -8,7 +8,8 @@ class C {
 var C = (function () {
     function C() {
     }
-    Object.defineProperty(C.prototype, "X", {
+    var proto_1 = C.prototype;
+    Object.defineProperty(proto_1, "X", {
         set: function (v) {
             if (v === void 0) { v = 0; }
         },