Note: don't use typeof x === 'object' to check whether something is a valid object, because it will return true for arrays as well.

Arrays are objects, so this is expected behaviour.

The core problem here is that you don't actually want to check if something is an object, but whether it matches the Human type. The correct way to do that is to define a type guard [0], for example:

  function isHuman(input: any): input is Human {
    return (
      Boolean(input) &&
      Object.prototype.hasOwnProperty.call(input, "name") &&
      Object.prototype.hasOwnProperty.call(input, "age")
    );
  }

There are libraries which can automate this for you which is the route I would recommend if you need to do this often. As you can see, the code to cover all edge cases such as `Object.create(null)` etc is not trivial.

[0] https://www.typescriptlang.org/docs/handbook/advanced-types....

pbowyer

> There are libraries which can automate this for you which is the route I would recommend

Which libraries do you recommend? I've had to do this a couple of times in my current project and it's painful (and I made mistakes).

Etheryte

Personally I really enjoy Typanion [0] since it's very similar to Yup [1] which I previously had extensive experience with. You can find more alternatives and a lengthy discussion about the whole problem space and its history in [2].

[0] https://github.com/arcanis/typanion

[1] https://github.com/jquense/yup

[2] https://github.com/microsoft/TypeScript/issues/3628