That site is generally aiming at providing
exact replacements, and quite a few of its examples are not great for various reasons:
Some use a bad technique; e.g. “Empty” removes the first child repeatedly, which is O(n²) in many environments, rather than removing the last child repeatedly, which is O(n), or `el.innerHTML = ""` which is shorter and more efficient in general)
Some suffer because they’re supporting IE which no one should do any more (fite me); e.g. “JSON” is long because it’s using XMLHttpRequest, but the Fetch API would make it vastly shorter (`data = await (await fetch('/my/url')).json()`—as an aside, suffix await like Rust settled on is so much nicer: `data = fetch('/my/url').await.json().await`); and “Each” should use `document.querySelectorAll(selector).forEach((el, i) => …)`; and “Matches Selector” is just `el.matches('.my-class')` now.
Also some look bad because jQuery optimised an operation that isn’t terribly common or should generally not be done, such as most of the width/height things (most uses of measuring element dimensions in JS are unnecessary, bad or wrong; aim to use CSS most of the time), “Index” (needing to know that an element is the nth child element is decidedly esoteric), “Type” (if you use this, you’re almost certainly doing the wrong thing), and “Parse HTML” (picture me running away, screaming in horror; this method is practically a primed security grenade). And remember, jQuery having optimised these things means you’re paying to ship that stuff that you’re not using.
And finally some seem more complex because they’re matching some unnecessary jQuery complexity, e.g. in “Set Height” (and alike in “Set Width”), $(el).height(…) takes a string, a number, or a function that returns a string or a number—but you’d be wiser to write `el.style.height = string;` or `el.style.height = number + 'px';` rather than being unnecessarily flexible.
Most people that use jQuery use a tiny subset of its functionality. The site is about showing that most uses of jQuery could actually dispense with it at little cost, if they’re the sort that value performance and such and want to ship less unnecessary code.