In the URL Standard, they are defined by Web IDL, which [defines them to be enumerable](https://heycam.github.io/webidl/#es-attributes). (Except [constructor](https://heycam.github.io/webidl/#interface-prototype-object) which is enumerable: false).
In the URL Standard, they are defined by Web IDL, which defines them to be enumerable. (Except constructor which is enumerable: false).