GET with parameters not just in the URL

In some http clients, e.g. jQuery.ajax, it’s possible to not just put the params in the URL but an object. The client will mix/concat the params into the URL later. Is that possible to give params independently like

fetch("foo.json" {
  method: "get",
  params: {
    param1: "value1",
    param2: "value2",
  }
}).then(response => response.json())

to come up with a URL /foo.json&param1=value1&param2=value2?

Also, sometimes the params may be longer than the length limitation, so that some APIs accept GET requests with a body of parameters. So I don’t understand the reason fetch couldn’t GET with the body like

fetch("foo.json" {
  method: "get",
  body: {
    param1: "value1",
    param2: "value2",
  }
}).then(response => response.json())

Will these be behaviors allowed in the future? Maybe I can submit a pull request for these.

[dgraham]

Query parameters may be encoded natively with encodeURIComponent or with jQuery.param.

[fingermark]

How is this solved today?