CODEWITHSUNDEEP
typescriptsvelte
Iainure
Iainure

Reputation: 199

Svelte allowing invalid typescript

I've been using the template referenced in this Svelte blog article to start learning about Typescript.

The app is building and serving fine. But I have some code like this:

<script lang="ts">
    let isDone: boolean = false;
    isDone = 'somestring'
    console.log(isDone)
</script>

I'm just starting out in Typescript, but shouldn't this be invalid? I'm not seeing any errors during npm run build or npm run serve. I don't use VS - is that where you'd expect this to be picked up?

Upvotes: 1

Views: 306

Answers (1)

dummdidumm
dummdidumm

Reputation: 5436

npm run build executes the build pipeline, which includes preprocessing the TypeScript contents inside Svelte files to JavaScript. This is a transpile-only process, because it happens on a per-file-basis. This means type checking during build would be incomplete/wrong. That's why there's a dedicated package called svelte-check, which does the type checking. It's included in the setupTypeScript.js-script of the template and can be invoked with npm run validate. There's also a watch mode for svelte-check if you'd like to run that alongside npm run dev. npm Link with a README on all the options: https://www.npmjs.com/package/svelte-check

Upvotes: 2

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