svelte2dts

Generate d.ts files from svelte files, creating truly sharable and well typed components!

Warning!

This package is still under heavy development. As far as I am aware, it works as intended. API can be considered as non-existent. Only the command has any level of support for now.

Installation

Install svelte2dts and its peer deps

npm i -D svelte2dts svelte2tsx typescript

Usage

After installing, you can invoke the command via npx or package.json.

Via CLI

Read all svelte files from ./src and generate d.ts files in ./types

npx svelte2dts --overwrite --runOnTS --declarationDir ./types ./src

Show help

npx svelte2dts --help

Configuring

package.json

Point package.json to the declarationDir and outDir. This is required to get the svelte VS-Code extension working properly. Note that they should not point into the same directory

{
  ...
  "svelte": "./preprocessed/index.js",
  "types": "./types/index.d.ts",
  ...
}

tsconfig.json

Be sure to set declarationDir and outDir to different locations.

{
  "compilerOptions": {
    "strict": true,
    "outDir": "./preprocessed",
    "declaration": true,
    "declarationDir": "./types"
  },
}

Note that with the above setup, you no longer need to specify --declarationDir in the command!

npx svelte2dts --overwrite --runOnTS ./src

Purpose

The only type of svelte components that are truly sharable are ones written in pure svelte, with no preprocessors such as typescript. As such, it is necessary to preprocess your components before publishing them. But sadly, svelte-preprocess removes all typings and does not generate any d.ts files. This is where we come in. We generate d.ts files for your sharable svelte components so your typings do not go to waste!

PITAs

Separate types directory is required

You MUST use a separate directory for types if you want the svelte plugin for vscode to work.

Markup preprocessors are not supported

If you have configured svelte to use a markup preprosessor by default (such as pug), you will have to:

1. run the markup preprocessors
2. run us on their output
3. finish preprocessing to create your sharable component.

I am considering writing a svelte preprocessor to intercept the code going into svelte-preprocess.typescript and generate the declarations from that.

tsc is still required

We only emit declarations for now. We do not compile your typescript into the configured outDir! As there are no real limitations stopping us from doing so we might add this feature in the future

src/MyComponent.svelte.d.ts is not copied to declarationDir

Typescript never copies d.ts files from src into declarationDir. We are trying not to deviate from their decisions too much. As such, if you want d.ts or svelte.d.ts files copied into declarationDir, you will need to do so with separate command.

My component is still not sharable!

Our only goal is to generate the sharable typings for your code. You will still require another package or script to generate a sharable component. A package that does both at the same time is next on my list to tackle

Q&A

My component is well typed in Vs-Code when used in .ts files, but not in .svelte files

Your types directory should not contain anything other than .d.ts and .svelte.d.ts files. If both Component.svelte and Component.svelte.d.ts exist, the svelte plugin will load the types from Component.svelte. To further the confusion, typescript will properly load types from the Component.svelte.d.ts file, causing types to work in .ts files even though they would not in .svelte files.

The solution is to specify both the svelte and types field in package.json as documented here and to ensure there are no .svelte files in the types directory.