Verify and document typescript + svelte-preprocessor working out of the box

[orta]

We think you can make a svelte project and just include the node modules for svelte-preprocessor to get lang='ts' support working. Verify that works and add some notes 👍

[dummdidumm]

Works like a charm https://github.com/dummdidumm/template

Differences to the javascript version

• Following npm packages are added: svelte-preprocess typescript tslib @rollup/plugin-typescript
• rollup.config.js is enhanced:

// ...
import sveltePreprocess from 'svelte-preprocess';
import typescript from '@rollup/plugin-typescript';

// ...
  plugins: [
    svelte({
      // ...
      preprocess: sveltePreprocess(), // <--
    }),

    // ...
    commonjs(),
    typescript(), // <-- added below commonjs
    // ...

Caveats:

• entry file (main.js) has still to be a javascript file

[swyxio]

tried this and verified!

[bgrand-ch]

Thanks for all your work! It seems that the file tsconfig.json is missing in the template:

rollup v1.32.1
bundles src/main.js → public/build/bundle.js...
(!) Plugin typescript: @rollup/plugin-typescript TS18003: No inputs were found in config file 'tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
[!] (plugin typescript) Error: @rollup/plugin-typescript: Couldn't process compiler options
Error: @rollup/plugin-typescript: Couldn't process compiler options
  at error (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/node-entry.js:5400:30)

The following tsconfig.json content is it OK?

{
  "include": ["src/**/*"],
  "exclude": ["node_modules/*"],
  "compilerOptions": {
    "target": "es2017",
    "types": ["svelte"],
    "moduleResolution": "node"
  }
}

rollup v1.32.1
bundles src/main.js → public/build/bundle.js...
(!) Plugin typescript: @rollup/plugin-typescript TS18003: No inputs were found in config file '/Users/bgd/Documents/Projects/Essential modules/tsconfig.json'. Specified 'include' paths were '["src/**/*"]' and 'exclude' paths were '["node_modules/*"]'.
[!] (plugin typescript) Error: @rollup/plugin-typescript: Couldn't process compiler options
Error: @rollup/plugin-typescript: Couldn't process compiler options
    at error (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/node-entry.js:5400:30)
    at throwPluginError (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/node-entry.js:11878:12)
    at Object.error (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/node-entry.js:12912:24)
    at emitParsedOptionsErrors (/Users/bgd/Documents/Projects/Essential modules/node_modules/@rollup/plugin-typescript/dist/index.js:310:17)
    at Object.buildStart (/Users/bgd/Documents/Projects/Essential modules/node_modules/@rollup/plugin-typescript/dist/index.js:469:13)
    at /Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/node-entry.js:13117:25
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async Promise.all (index 2)

Source: https://codechips.me/how-to-use-typescript-with-svelte/

[dummdidumm]

Interesting ... I didn't even need a tsconfig.json so I just left it out. I did not get either of those errors.

[hellpirat]

I trying to use it with sapper and now I got this error.

$ sapper dev
✗ server
@rollup/plugin-typescript: Couldn't process compiler options
✗ client
@rollup/plugin-typescript: Couldn't process compiler options
internal/modules/cjs/loader.js:584
    throw err;

export const preprocess = sveltePreprocess({
  postcss: true,
  style: sass(),
})

 plugins: [ 
    ...
    ...
    svelte({
        dev,
        hydratable: true,
        emitCss: true,
        preprocess,
      }),

     ...
    ....
     commonjs(),
      typescript(),

[dummdidumm]

The template was intended as a proof of concept that the IDE works out of the box with svelte. Things like tsconfig.json or Sapper were not on my mind at that time.
Typescript with Sapper in general is not supported well right now I think - @benmccann do you know more about that?

[benmccann]

Things are close to working with Sapper. There's two main issues:

1. Sapper swallows errors related to TypeScript. This is fixed in master, but not yet released. That could be why you just see "Couldn't process compiler options" and not a more helpful message
2. You can't use TypeScript with templates with preload in them yet. There's a PR pending that would fix this: TypeScript support: don't try to compile templates sapper#1222

I made a fork of Sapper that you can use to code in TypeScript until the above fixes get merged and released: sveltejs/sapper#760 (comment)

[bgrand-ch]

@dummdidumm Thanks for your quick response 🙂

Unfortunately, the problem persist.

This is my package.json file:

{
  "name": "svelte-app",
  "version": "0.0.1",
  "scripts": {
    "build": "npm install && rollup -c",
    "dev": "npm install && rollup -c -w",
    "start": "sirv public --single",
    "lint": "eslint . --ext .js,.svelte; exit 0",
    "lint-report": "eslint . --ext .js,.svelte -o ./.eslint-report.html -f html; exit 0"
  },
  "devDependencies": {
    "@rollup/plugin-commonjs": "11.0.2",
    "@rollup/plugin-node-resolve": "^7.0.0",
    "@rollup/plugin-typescript": "^4.1.2",
    "eslint": "^7.0.0",
    "eslint-config-standard": "^14.1.1",
    "eslint-plugin-import": "^2.20.2",
    "eslint-plugin-node": "^11.1.0",
    "eslint-plugin-promise": "^4.2.1",
    "eslint-plugin-standard": "^4.0.1",
    "eslint-plugin-svelte3": "^2.7.3",
    "rollup": "^1.20.0",
    "rollup-plugin-livereload": "^1.0.0",
    "rollup-plugin-svelte": "^5.0.3",
    "rollup-plugin-terser": "^5.1.2",
    "svelte": "^3.0.0",
    "svelte-preprocess": "^3.8.0",
    "tslib": "^2.0.0",
    "typescript": "^3.9.5"
  },
  "dependencies": {
    "page": "^1.11.6",
    "sirv-cli": "^0.4.4"
  }
}

and the rollup.config.js file:

import svelte from "rollup-plugin-svelte";
import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import livereload from "rollup-plugin-livereload";
import { terser } from "rollup-plugin-terser";
import autoPreprocess from "svelte-preprocess";
import typescript from "@rollup/plugin-typescript";

const production = !process.env.ROLLUP_WATCH;

export default {
  input: "src/main.js",
  output: {
    sourcemap: true,
    format: "iife",
    name: "app",
    file: "public/build/bundle.js"
  },
  plugins: [
    svelte({
      // enable run-time checks when not in production
      dev: !production,
      // we'll extract any component CSS out into
      // a separate file - better for performance
      css: css => {
        css.write("public/build/bundle.css");
      },
      preprocess: autoPreprocess()
    }),

    // If you have external dependencies installed from
    // npm, you'll most likely need these plugins. In
    // some cases you'll need additional configuration -
    // consult the documentation for details:
    // https://github.com/rollup/plugins/tree/master/packages/commonjs
    resolve({
      browser: true,
      dedupe: ["svelte"]
    }),
    commonjs(),
    typescript(),

    // In dev mode, call `npm run start` once
    // the bundle has been generated
    !production && serve(),

    // Watch the `public` directory and refresh the
    // browser on changes when not in production
    !production && livereload("public"),

    // If we're building for production (npm run build
    // instead of npm run dev), minify
    production && terser()
  ],
  watch: {
    clearScreen: false
  }
};

function serve () {
  let started = false;

  return {
    writeBundle () {
      if (!started) {
        started = true;

        require("child_process").spawn("npm", ["run", "start", "--", "--dev"], {
          stdio: ["ignore", "inherit", "inherit"],
          shell: true
        });
      }
    }
  };
}

[dummdidumm]

I cannot reproduce the error myself. But looking at your package.json it seems you use rollup 1.x instead of 2.x . Maybe bumping all dependencies to the latest version fixes it for you?

[bgrand-ch]

@dummdidumm I bumped all dependencies to their latest version. I deleted my custom tsconfig.json file, the package-lock.json file and the node_modules folder. The problem persist 🤔

Error message:

rollup v2.15.0
bundles src/main.js → public/build/bundle.js...
(!) Plugin typescript: @rollup/plugin-typescript TS18003: No inputs were found in config file 'tsconfig.json'. Specified 'include' paths were '["**/*"]' and 'exclude' paths were '[]'.
[!] (plugin typescript) Error: @rollup/plugin-typescript: Couldn't process compiler options
Error: @rollup/plugin-typescript: Couldn't process compiler options
    at error (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/rollup.js:213:30)
    at throwPluginError (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/rollup.js:17117:12)
    at Object.error (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/rollup.js:17911:24)
    at emitParsedOptionsErrors (/Users/bgd/Documents/Projects/Essential modules/node_modules/@rollup/plugin-typescript/dist/index.js:310:17)
    at Object.buildStart (/Users/bgd/Documents/Projects/Essential modules/node_modules/@rollup/plugin-typescript/dist/index.js:469:13)
    at /Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/rollup.js:18109:25
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at async Promise.all (index 2)
    at Object.rollupInternal (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/rollup.js:19099:9)
    at Task.run (/Users/bgd/Documents/Projects/Essential modules/node_modules/rollup/dist/shared/watch.js:715:28)

Svelte VS Code extensions installed:

• Svelte 3 Snippets - v0.4.0
• Svelte Beta - v99.0.41
• Svelte Intellisense - v0.7.1

Others VS Code extensions installed:

• Auto Close Tag - v0.5.7
• Bracket Pair Colorizer - v1.0.61
• ESLint - v2.1.5
• JavaScript Booster - v0.12.3
• Material Icon Theme - v4.1.0
• NativeScript - v0.11.0
• NativeScript Extend - v2.11.10
• npm - v0.3.12
• npm Intellisense - v1.3.0
• Path Intellisense - v2.2.0
• PHP Intelephense - v1.4.1
• Twig Language 2 - v0.9.1
• Vetur - v0.24.0

package.json file:

{
  "name": "svelte-app",
  "version": "0.0.1",
  "scripts": {
    "build": "npm install && rollup -c",
    "dev": "npm install && rollup -c -w",
    "start": "sirv public --single",
    "lint": "eslint . --ext .js,.svelte; exit 0",
    "lint-report": "eslint . --ext .js,.svelte -o ./.eslint-report.html -f html; exit 0"
  },
  "devDependencies": {
    "@rollup/plugin-commonjs": "^13.0.0",
    "@rollup/plugin-node-resolve": "^8.0.1",
    "@rollup/plugin-typescript": "^4.1.2",
    "eslint": "^7.2.0",
    "eslint-config-standard": "^14.1.1",
    "eslint-plugin-import": "^2.21.2",
    "eslint-plugin-node": "^11.1.0",
    "eslint-plugin-promise": "^4.2.1",
    "eslint-plugin-standard": "^4.0.1",
    "eslint-plugin-svelte3": "^2.7.3",
    "rollup": "^2.15.0",
    "rollup-plugin-livereload": "^1.3.0",
    "rollup-plugin-svelte": "^5.2.2",
    "rollup-plugin-terser": "^6.1.0",
    "svelte": "^3.23.1",
    "svelte-preprocess": "^3.9.7",
    "tslib": "^2.0.0",
    "typescript": "^3.9.5"
  },
  "dependencies": {
    "page": "^1.11.6",
    "sirv-cli": "^0.4.6"
  }
}

rollup.config.js file:

import svelte from "rollup-plugin-svelte";
import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import livereload from "rollup-plugin-livereload";
import { terser } from "rollup-plugin-terser";
import autoPreprocess from "svelte-preprocess";
import typescript from "@rollup/plugin-typescript";

const production = !process.env.ROLLUP_WATCH;

export default {
  input: "src/main.js",
  output: {
    sourcemap: true,
    format: "iife",
    name: "app",
    file: "public/build/bundle.js"
  },
  plugins: [
    svelte({
      dev: !production,
      css: css => {
        css.write("public/build/bundle.css");
      },
      preprocess: autoPreprocess()
    }),
    resolve({
      browser: true,
      dedupe: ["svelte"]
    }),
    commonjs(),
    typescript(),
    !production && serve(),
    !production && livereload("public"),
    production && terser()
  ],
  watch: {
    clearScreen: false
  }
};

function serve () {
  let started = false;

  return {
    writeBundle () {
      if (!started) {
        started = true;

        require("child_process").spawn("npm", ["run", "start", "--", "--dev"], {
          stdio: ["ignore", "inherit", "inherit"],
          shell: true
        });
      }
    }
  };
}

svelte.config.js file:

const autoPreprocess = require("svelte-preprocess");

module.exports = {
  preprocess: [
    autoPreprocess()
  ]
};

[AlexandreCantin]

@elvticc I've got the same problem.

To fix it, I have :

1. renamed main.js to main.ts
2. And in rollup.config.json, changed : input: 'src/main.js' to input: 'src/main.ts'
   (Note : You need to have a tsconfig.json too)

I know, dummdidumm said entry file (main.js) has still to be a javascript file but it doesn't work for me 😕

[dummdidumm]

Very interesting, seems like there is still some Vodoo to these setups - glad you got it working anyway! I will head over to the core svelte repo to discuss creating an official typescript template there.