this refer to component/custom element instance

[hontas]

resolves #3593

Call instance-function with component as this to be able to reference root/custom element.

Now it's possible to reference it like so:

<svelte:options tag="custom-element" />
<div bind:this={topEl} />

<script>
import { onMount } from 'svelte';

let custemElementInstance;
let topEl;

onMount(() => {
  custemElementInstance =  topEl.parentNode.host.parentElement
});
</script>

With this change we could simply use this keyword.

<svelte:options tag="custom-element" />

<script>
import { onMount } from 'svelte';

onMount(() => {
  this.shadowRoot.querySelector('xxx');
});
</script>

[Conduitry]

It looks like this would given all components access to their own instance, which isn't something we want to do (because, among other things, it would mean that components could now programmatically destroy themselves, which would wreak havoc).

I'm not so sure that #3539 is something we want with custom elements either. If the real goal is to solve something like #3119, that's where the focus should be.

[hontas]

@Conduitry I'm happy to update the PR so that this only targets custom elements if that makes things better?

[hontas]

Updated my branch to only do this for custom elements

[tanhauhau]

instead of this, a better alternative is to get $$host which exist only for custom elements

#3091