feat(nuxt): add onNuxtReady composable

[danielroe]

🔗 Linked issue

resolves nuxt/nuxt#15719

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This adds a new onNuxtReady composable. It allows running a callback after your app has finished initializing. It is ideal for running code that should not block the initial rendering of your app.

export default defineNuxtPlugin(() => {
  onNuxtReady(async () => {
    const myAnalyticsLibrary = await import('my-big-analytics-library')
    // do something with myAnalyticsLibrary
  })
})

It is 'safe' to run even after your app has initialized. In this case, then the code will be registerd to run in the next idle callback.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codesandbox]

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[HigherOrderLogic]

Isn't it more ideal to make this a hook? Something like app:ready?

[danielroe]

There is already such a hook, which this composable uses internally.

[pi0]

LGTM 💯