if-else case caused every element update

[yisar]

const node = document.getElementById("app")

const setState = state => {
  patch(
    node,
    h("div", {}, 
      state && h("h1", {}, 'hello'),
      h("button", { onClick: () => setState(!state) }, "x")
    )
  )
}

setState(true)

I‘d seen that only keyd elements can be cached and reused, and elements like this are still completely updated. In fact, the following use case only needs to insert or remove hello

What do you think of this?

[jorgebucaran]

Insertions are difficult and in some cases impossible to optimize without keys, so use keys -- that's one of the reasons they exist.