Should Vite do type-checking on builds by defaults? (Why tsc -b && vite build instead of just vite build)

[arcataroger]

Hi there,

I have a philosophical / design question about how the default create-vite build settings are meant to work. Currently, most of the templates are using some variation of tsc -b && vite build, which causes tsc to run and do its own type-checking before the actual project is subsequently rebuilt using esbuild.

Is this on purpose? We ran into a situation (now solved, see #18512) where an imported third-party lib's type error was causing a build to fail. It seems odd to me that this would happen, since usually end-user devs have no control over third-party type errors.

There's also some discrepancies between various Vite docs & templates:

Sources saying NOT to type-check before build

• The getting started docs do not say to use tsc before vite build
• The Features/TypeScript section implies that Vite should be transpile-only, and builds can be manually type-checked only if necessary and if the IDE doesn't do it already
• The Svelte.js template does not include tsc

Sources saying TO type-check before build

• Most of the templates DO run tsc -b first, like for React
• Vanilla TS runs tsc without the -b (build) flag
• Vue runs its own tsc with the -b flag

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So, I'm just trying to understand the design choice behind this (if it was indeed intentional at all). Should build-time type checking (and potentially build-halting) be included by default? And if so, is there a reason it's different across templates?

[rschristian]

I think you've misunderstood some of the links.

The getting started docs do not say to use tsc before vite build

Omission does not mean "do not use tsc before vite build". This link is just documenting the Vite CLI which tsc is not part of.

The Features/TypeScript section implies that Vite should be transpile-only, and builds can be manually type-checked only if necessary and if the IDE doesn't do it already

It's saying type checking is not a Vite concern or responsibility, but if you want that, you'll can use tools (tsc). No where does it state "builds can be type-checked only if necessary"

The Svelte.js template does not include tsc

I don't believe you can run tsc against Svelte files, it wouldn't know how to parse them correctly, hence why svelte-check is used just two lines below where you link.

[arcataroger]

Well, the ambiguity is why I'm seeking clarity. It's not clear to me whether the omission is deliberate. It's a fair question, isn't it, of whether type-checking should halt a build by default – precisely because that's not really even a part of Vite / esbuild?

The svelte-check is still a separate command, btw, not part of the build command for that template.

It's not a huge deal either way. People who want it (or don't know about it) can just leave it in there. People who don't want that forced type-checking can remove tsc from the build command and it still builds fine. But I'm just trying to understand the philosophy behind this. Can't tell from the docs & templates whether it's just an oversight or whether it was put there on purpose.

[rschristian]

I don't see any ambiguity tbh.

Whether you run a type-checking step, and how you run it, is entirely up to you -- it's outside the scope of Vite. The TS templates (and only the TS templates) come with a script to check types as it was asked for, but it's not a prescribed solution. You can do as you like.

I don't think there is any philosophy, it's just a "here's how you do it if you want it".

[arcataroger]

Alright then, I guess that's that.