feat: add async support for vite config file

[xiaoxiangmoe]

Description

feat: add async support for vite config file

for example:
If the config needs to call async function, it can export a async function instead:

export default async ({ command, mode }) => {
  const data = await asyncFunction();
  return {
    // build specific config
  } 
}

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[patak-dev]

This looks good. How would it work when using defineConfig ? Do we need a defineAsyncConfig utility?

Edit: It could be used like

import { defineConfig } from 'vite'

export default async ({ command, mode }) => {
  const data = await asyncFunction();
  return defineConfig({
    // build specific config
  })
}

but it would be nice to have

import { defineAsyncConfig } from 'vite'

export default defineAsyncConfig(async { command, mode }) => {
  const data = await asyncFunction();
  return {
    // build specific config
  }
})

That also type checks command and mode. What do you think? I think it is ok if you prefer to discuss this in another PR.

[Shinigami92]

I think export default defineConfig(async ({ command, mode }) => { // ... should be just enough
And then handle it correctly in the defineConfig dependently

The really nice thing behind defineConfig should be that it is just usable/addable as easy as possible

- export default config
+ export default defineConfig(config

- export default () => 
+ export default defineConfig(() =>

- export default async () => 
+ export default defineConfig(async () =>

[Shinigami92]

There are two smart ways of handle this: https://stackoverflow.com/questions/27746304/how-do-i-tell-if-an-object-is-a-promise

First would be to check if it's a promise, or second (and I think this is really smart ^^) just use Promise.resolve(configFn).then

[xiaoxiangmoe]

@Shinigami92 We can just use await

[Shinigami92]

Seems it's not my day 😆 and I'm thinking far to complicated

[xiaoxiangmoe]

@yyx990803 Anything else should I do?

[patak-dev]

@xiaoxiangmoe if you would like to modify defineConfig in a separate PR (or prefer that others would do it), then there is nothing to do for this one. But I think we should have that modification before merging this PR for consistency.

Edit: Ok, IMO we can merge this as is but it would be good to have that modification soon. We can use it like this until that time:

import { defineConfig } from 'vite'

export default async ({ command, mode }) => {
  const data = await asyncFunction();
  return defineConfig({
    // build specific config
  })
}

Note: Evan needs would need to approve this one.

[Shinigami92]

@patak-js I'm not sure if you're messing something up, but I would thing it would be this way 🤔:

import { defineConfig } from 'vite'

export default defineConfig(async ({ command, mode }) => {
  const data = await asyncFunction();
  return {
    // build specific config
  }
}

[patak-dev]

@Shinigami92 updated my wording, the code snippet was referring to how it can be used until we modify defineConfig to support async functions.

[xiaoxiangmoe]

Note: Evan needs would need to approve this one.

@yyx990803 Can you review it?

[patak-dev]

Hey @xiaoxiangmoe, we are using GitHub's review requests when we need Evan's input so he can look at all the issues and PR that require his attention when he is focusing on Vite. There is no need to explicitly ping him with an extra message.

[xiaoxiangmoe]

Oh, I know. Sorry.
GitHub's review requests is great.