Add JSON convenience methods

[jodiedunlop]

To simplify json calls, which is probably the major use-case of this library it might be nice to provide some wrapper methods which simplify the api calls even further for the common get, put, patch, delete http verbs.

Eg.

const json = await ky.getJson('https://some-api.com');
const json = await ky.postJson('https://some-api.com', {foo: true});

These would obviously just be some syntatic sugar around the existing json examples, but imo it would make the api even nicer to use.

[szmarczak]

The readme says:

Returns a Response object with Body methods added for convenience. So you can, for example, call ky.json() directly on the Response without having to await it first

[sindresorhus]

To make it clear, you won't save many characters with your proposal. 1 character to be exact. You can't really pass a plain object into the second one as we need to support options too. So would be:

const json = await ky.getJson('https://some-api.com');
const json = await ky.postJson('https://some-api.com', {json: {foo: true}});

vs. Ky now:

const json = await ky('https://some-api.com').json();
const json = await ky.post('https://some-api.com', {json: {foo: true}}).json();

The current Ky syntax is almost the same size, but is much more flexible. You can decide to send JSON, but receive something else, all without having to learn a different API.