Subscribe on changes!

defineEmits with typescript and union types raises a warning

avatar
Mar 22nd 2023

Vue version

3.2.47

Link to minimal reproduction

https://sfc.vuejs.org/#eNpNUMtuwkAM/BXLF0CC5J4uqD30L3wJwcDS7ENrh6qi/Hu9SaX2tPbszHg0D3zLublPjB065ZDHXvlAEcAdJ9UU4XUY/fCxJ+Tgdb2SFHi1ITzMMAR27UI0kWv/OTgZis8KwjplGPt4MQ8VU1LUr8zwbn4CeyCsnoTwbWM9QvhCcUhRFOpqlBOffeRZ4B413Jq7Rb/p4J78yQQLSNjHpFcuhFu492MHosXHyx/veVhv7HHtks/S4BZ9yKnoLvS5uUmKVsZ8hn4/LHUHM1Ixa6vuhFfVLF3bynmoFd6kSeXS2tSUKaoP3LCE3bGkT+FixoTV4mkZ8PkDyDyALQ==

Steps to reproduce

click the button that says click me

What is expected?

some event is emitted without warning

What is actually happening?

A warning is raised Component emitted event "some" but it is neither declared in the emits option nor as an "onSome" prop.

System Info

No response

Any additional comments?

The warning is only raised due to the presence of another defined event. If the another event is not defined, the some event is registered properly. ie the following works properly:

type Emits = "some" | "emit";
const emit = defineEmits<{
  (e: Emits): void;
}>();
avatar
Mar 22nd 2023

The warning is only raised due to the presence of another defined event. If the another event is not defined, the some event is registered properly. ie the following works properly:

Not exactly. When you remove "another", no event is being registered at all (check the generated JS tab on the right). what however would work currenty, is writing the union inline:

const emit = defineEmits<{
  (e: "some" | "emit"): void;
  (e: "another", val: string): void;
}>();

So this is a current compiler limitation where it does not resolve type aliases used in event names.

avatar
Mar 23rd 2023

I see, thanks for clearing that up :). I guess for now I'll just live with the warning, or maybe I'll disable it, since I'm importing the Emits type from another module and don't want to duplicate it.

Maybe at some point the compiler will pickup on union types, but no rush. Typescript provides enough safety for me to be comfortable with the current behaviour.

avatar
Mar 23rd 2023

You can try betterDefine in Vue Macros.

P.S. Sorry I didn't know the issue will be closed via cross-repo commit.