Why doesn't the "body" member of RequestInit have a default value?

[bzbarsky]

The member is defined at https://fetch.spec.whatwg.org/#dom-requestinit-body as follows:

  BodyInit? body;

The only consumer of the RequestInit dictionary is https://fetch.spec.whatwg.org/#dom-request which does this:

If either init["body"] exists and is non-null or inputBody is non-null, and request’s method is GET or HEAD, then throw a TypeError.

and

If init["body"] exists and is non-null, then:

In both cases, "does not exist" and "exists but is null" are treated identically, so it seems like the IDL could just say:

BodyInit? body = null;

and not worry about the "does not exist" case.

[annevk]

Step 14 of the constructor reads

If init is not empty, then:

which would be affected by this change.

What is a little weird to me though is that if you do new Request(oldRequestWithBody, { body: null }) it doesn't seem like the body would get cleared. Maybe I'm missing something with disturbed/locked though, would have to investigate more deeply.

[bzbarsky]

Ah, good catch re step 14. So I guess then the question is indeed what should happen in the { body: null } but nothing else set case.

[annevk]

x = new Request("about:blank", { method: "POST", body: "test" });
copyX = new Request(x, { body: null });
copyX.text().then(console.log);

gives "test" in all browsers.

Is this something we want to fix?

cc @wanderview @youennf @evilpie

[wanderview]

cc @yutakahirano