Make an HTTP request. Parse the JSON body if a 200, otherwise log an error.
fetch(url)
.then(res => res.status === 200 ? res.json() : Promise.reject(res))
.then(data => { ... })
For some things, like those mentioned by twhb, where support is >90%, sure, ditch the library and use the supported stuff. But I don't think all of jQuery is that well supported, yet, and/or has as decent an interface.
https://github.com/github/fetch or https://www.npmjs.com/package/fetch-ie8
I believe that jQuery is not "modular" enough for today's web development environment. The "light" version is a step in the right direction but it's not enough. If one could configure the "modules" needed and download/load a single file/library, it would be tremendous.