//// [genericConstraint1.ts] class C { public bar2(x: T, y: U): T { return null; } } var x = new C(); x.bar2(2, ""); //// [genericConstraint1.js] var C = (function () { function C() { } C.prototype.bar2 = function (x, y) { return null; }; return C; })(); var x = new C(); x.bar2(2, "");