create-svelte: Skip prompts by passing args to CLI

[JReinhold]

This PR makes it possible to skip some or all prompts when creating a new SvelteKit project with the create-svelte package. eg.:

npm create svelte@latest my-app \
  --name=my-new-app \
  --template=default \
  --types=checkjs \
  --prettier  \
  --no-eslint \
  --no-playwright

The problem

In Storybook we have a system for creating new projects with the different frameworks programmatically, to continuously ensure Storybook works out of the box with all the frameworks. But that's a bit hard for us to do with SvelteKit, because create-svelte is an interactive experience and thus not easy to automate.

Instead of hacking around it internally in Storybook I thought it would be better to solve it for everyone. This is also useful in tutorial/guide situations where an author wants to simplify the learning path by removing prompts that a beginner might not understand.

The solution

As per the example in the prompts docs, yargs is used to implicitly override any of the prompts if they are passed as named arguments. The implicitness is important here, because it means that if we add or change the prompts later they will automatically be overwritable by args.

I have not documented this feature in the official docs because there didn't seem to be a good place to do it. I'm open to add it somewhere though if you think it makes sense.
It is however documented in the package's readme similarly to how the programmatic API is documented.

Please don't delete this checklist! Before submitting the PR, please make sure you do the following:

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• This message body should clearly illustrate what problems it solves.
• Ideally, include a test that fails without this PR but passes with it.

Tests

• Run the tests with pnpm test and lint the project with pnpm lint and pnpm check

Changesets

• If your PR makes a change that should be noted in one or more packages' changelogs, generate a changeset by running pnpm changeset and following the prompts. All changesets should be patch until SvelteKit 1.0

[changeset-bot]

🦋 Changeset detected

Latest commit: 48b1e45

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[JReinhold]

this makes it so that --types=none ends up as { types: null } internally.

Alternatively we could make the arg match one-to-one either by making the arg null instead of "none", or changing the internal null to be "none" everywhere.

[Conduitry]

Thank you, but this isn't something we want to add. See, most recently, #6117 (comment) for more information.

[JReinhold]

Oh wow sorry for wasting your time. My searching came up empty.

[dummdidumm]

Note that you can still use create-svelte programmatically, see the API section of its readme. That should help you; you can create a JS script that calls create-svelte the way you want and invoke that script.

[Ni55aN]

@dummdidumm the problem is that then you need to install the package and you can not use it through npx

[JReinhold]

@Ni55aN I've created a separate package for this that might suit your needs. I attempt to keep it up-to-date regularly. https://github.com/storybookjs/create-svelte-with-args

[Ni55aN]

@JReinhold thanks, opted for this package ✔

https://github.com/retejs/rete-kit/blob/1f713d3431a994d8782c674133ad924d258c0402/src/app/stack/svelte/index.ts#L17-L23