on:*

[matyunya]

#2837

This is first iteration of on:* to enable forwarding arbitrary events for components.

[Conduitry]

This would give on:any a different meaning than it already has, which we don't want to do. It's possible that someone has code where they are bubbling an event called any, and this would break it. I think elsewhere should just be looking for handler.name === '*' directly.

[matyunya]

Renaming to $$any helped. Is it ok way this way?

[Conduitry]

Unless I'm mistaken, this mechanism won't forward events with handlers attached after the component has been mounted.

[matyunya]

Demo is available here: https://public-mo2fyuk8g.now.sh/.

I couldn't find another way but to write block specific code (so far each and if) to push up elements with on:*. I know that this is missing disposing of listeners, also no need to generate any_handler. Anything else I'm overlooking here?

[matyunya]

Here's component I'm testing on:

<script>
  import { createEventDispatcher } from "svelte";
  export let value = null;

  const dispatch = createEventDispatcher();

  const arr = [1,2,3];

  function handleClick() {
    value = !value;

    dispatch('any');
  }
</script>

<button on:* on:click={handleClick}><slot /></button>
 
<div on:*></div>
<div on:*></div>
{#if value}
  <button on:*>another button</button>
  {#each arr as k}
    <button on:*>{k}</button>
  {/each}
{/if}

What other cases should I consider besides else and await?

[matyunya]

One more thing. listen is tree shaken if there are only on:* event handlers. What can I do to force keep it?

[codecov-io]

Codecov Report

Merging #3349 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3349   +/-   ##
=======================================
  Coverage   50.25%   50.25%           
=======================================
  Files           1        1           
  Lines         197      197           
=======================================
  Hits           99       99           
  Misses         98       98

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[matyunya]

Anything I can do to stop being ignored?

[jerriclynsjohn]

@matyunya I was able to compile your specific package locally and tried an event forwarding with the example given at https://svelte.dev/tutorial/event-forwarding, and instead of using on:message in Outer.svelte I tried using on:* and couldn't get the event to be forwarded. Am I missing something here or is it not working?

[ghost]

Is this something that is still desired?

The code needs to be rewritten since this was done before code-red and ast stuff was merged.

I'd recommend also branching for PR instead of submitting from master. It makes rework and rebasing much easier.

[matyunya]

I made the first step here and wanted to hear feedback if my direction is right. Will make another round now.

[ghost]

@matyunya,

You really should do a branch since there's now commit pollution on this PR from your other strict-order PR. I tend to never work on my own fork master and instead just fast-forward to the upstream and then rebase my branches off of that (instead of merge commits).

When I first looked at the notification email for this PR, it said there were 200+ commits added, which is pretty good sign that the workflow is a off somewhere.

See if you can untangle this from the other PRs so it can get a proper review.
There's been some talk of this feature on Discord so I'm pretty sure it will be a welcomed addition, provided that the merge isn't messy.

[matyunya]

My bad.

I will recreate my fork and put the two features in different branches. But given the diff with master, I'll have to do my work on on:* from scratch, maybe find a leaner solution along the way.

[PaulMaly]

@matyunya Any news here? Seems it's the most wanted feature at the current moment.

[kkarpeev]

Yeah. Ability to forward all events not only from a DOM-node but also through components is really REALLY necessary.

[Leonidaz]

I believe this is the PR that was considered last for this feature, pending a review from another core team member: #4599