Defaults to TS for `<script vapor>`

[sxzz]

Discussion: Should lang default to ts in Vapor SFCs?

<script vapor>

This would make it behave like a non-Vapor component:

<script setup lang="ts">

Please leave a 👍 or 👎 reaction below.

[unpseudocomplique]

One of the vue main sell point is easy adoption.
This would make it harder for junior.
I don't mind keeping lang="ts" it's super easy with a snippet

[sxzz]

It's worth mentioning that TS can essentially be considered a superset of JS. Enabling TS automatically does not require users to use types mandatorily.
Astro also enables TypeScript by default.

[ubugeeei]

Wouldn't it be a high cognitive load for users if the interface is not aligned with other modes?
In the case of Normal Mode, the default is setup="false" lang="js", and in the case of Vapor Mode, the default is setup="true" lang="ts", which seems a bit difficult to predict.

Some may argue that having documentation would solve the issue, but personally, I think predictability through a unified interface is important.

Astro also enables TypeScript by default.

If you want to default to TS, shouldn't we first raise an RFC in vuejs/core rather than here, so that vapor and non-vapor can be unified?

When marking Vapor Mode in the script attribute, I thought it would be better to have an interface like the following:

<script setup lang="ts" vapor>

</script>

---

Initially, there was a suggestion of using *.vapor.vue, but is it not necessary to first discuss whether it should be represented by attributes or file extensions? 🫠

[sxzz]

• Because Vapor does not intend to support non-setup SFCs. setup is also not a good name. Therefore, in Vapor, we decided to use vapor to replace setup (not actually setting setup=true at the low level).
• Regarding *.vapor.vue, considering this will make the filename longer. It will also inevitably lengthen the import statements. Imagine an extreme case App.ce.vapor.client.vue.
• Regarding the default enabling of TS in vuejs/core, this is a breaking change because there are slight inconsistencies between TS and JS, especially for JSX.

[RihanArfan]

From my understanding, Vapor requires a build step to compile into runtime code. Given Vue works fantastically with TypeScript brings, I think a default of TS is sensible.

[ubugeeei]

Because Vapor does not intend to support non-setup SFCs.

Shouldn't non-setup scripts be supported?

For example, I have seen projects that write code like the following (in fact, I often use it myself).

<!-- DialogA.vue -->

<script lang="ts">
export function useDialogA() {
  /* ... */
  return {/* ... */}
}
</script>

<script setup lang="ts">
// some setup script
</script>

<template>
  <!-- ... -->
</template>

If non-setup scripts are not supported, we cannot export anything from the SFC.

[sxzz]

About non-setup scripts, I haven't figured this out yet, let's leave this topic for another thread.

[pavi2410]

How about

<script> // options API
<script setup> // composition API
<script setup=vapor> // vapor mode

all defaults to lang=js

[ubugeeei]

There may be two ways to indicate attributes, where to focus on them?
(It's quite impromptu, I haven't thought deeply about it.)

<!-- If you want to focus on the attributes of the script as "SFC settings" -->
<script setup="vapor">
</script>

<template>
</template>

<!-- If you want to focus on the settings of the template (outputting a renderer that does not use virtual DOM) without affecting the setup -->
<script setup>
</script>

<template vapor>
</template>

In the latter case, the script remains the same as before.

[MuhammadM1998]

Couldn't it be a compiler option that defaults to lang=js? Similar to having an option to enable vapor mode globally. It would pertain the same behavior while giving those who prefer lang=ts to set it globally with one line. This could be implemented for reglar setup too not just vapor

[icarusgk]

I think we should keep Vapor's behavior predictable. Replacing the setup attribute with the vapor attribute, to turn on Vapor Mode, would do it for most people 🙌🏼

<!-- Defaults to lang="js" as `setup` does -->
<script vapor>

</script>

<!-- Manually opt-in to TypeScript with lang="ts" keeping the same behaviour -->
<script vapor lang="ts">

</script>

[fimion]

Unless lang="ts" is a requirement for vapor mode, then it should not be the default.

[fimion]

I will also point out that this would be the only instance (I can think of) in a sfc where an attribute other than lang specifies what the compiler language is.

[michaelpumo]

I have to echo what @icarusgk said, that script should default to JS.

<script lang="ts" vapor>
</script>

...is clear to me.