//// [overloadOnConstInheritance4.ts] interface I { x1(a: number, callback: (x: 'hi') => number); } class C implements I { x1(a: number, callback: (x: 'hi') => number); x1(a: number, callback: (x: 'hi') => number) { } } //// [overloadOnConstInheritance4.js] var C = (function () { function C() { } C.prototype.x1 = function (a, callback) { }; return C; })();