//// [subtypingWithOptionalProperties.ts] // subtyping is not transitive due to optional properties but the subtyping algorithm assumes it is for the 99% case // returns { s?: number; } function f(a: T) { var b: { s?: number } = a; return b; } var r = f({ s: new Object() }); // ok r.s && r.s.toFixed(); // would blow up at runtime //// [subtypingWithOptionalProperties.js] // subtyping is not transitive due to optional properties but the subtyping algorithm assumes it is for the 99% case // returns { s?: number; } function f(a) { var b = a; return b; } var r = f({ s: new Object() }); // ok r.s && r.s.toFixed(); // would blow up at runtime