Transition's @appear hook invoked even when appear not specified / falsy

[pkaminski]

Version

2.5.22

Reproduction link

https://codepen.io/anon/pen/jXdLGV

Steps to reproduce

Open the repro and note that the rendered page says "initial appear".

What is expected?

The @appear hook should not be invoked and the page should just say "initial".

What is actually happening?

The @appear hook is invoked even though the transition doesn't have an appear attribute, and hence shouldn't be triggering on appear. The same thing happens if you add :appear ="false" to the transition.

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Ran into this when building some custom transition components where appear should be user-controlled, but was being invoked all the time instead.

[posva]

It's also worth noting that we could improve the docs in this matter: https://vuejs.org/v2/guide/transitions.html#Transitions-on-Initial-Render

I'm not sure what is exactly expected here, but I would also say no appear events if appear=false. It seems there is a done callback to it

[Itisfilipe]

Hey guys! I am learning this code base so I have implemented a fix for that without knowing if that would be ever needed, feel free to review it if you find it useful or disregard if not. Thanks!

[shasharoman]

I think this is not a code bug, but the document needs to be described more clearly.

Both appear attribute and @appear hook will cause an appear transition, and @appear hook will have a higher priority. If you don't want an appear transition, don't specify @appear hook. Because @appear hook has a higher priority, using :appear=false does not cancel the transition.