How to Add TypeScript Types in Vite Library Mode

Introduction When building a component library with Vite and Vue.js, it's essential to ensure that your TypeScript types are included in the final build. If you've followed the Vite documentation for library mode and defined props and interfaces in your components but find that types are missing from the final output, this article will guide you through the necessary steps to include those types. Understanding the Issue The common challenge faced when building libraries using Vite is ensuring that TypeScript type definitions are generated and included. This can happen for various reasons, including misconfigurations in your tsconfig.json file or missing options in your Vite configuration. Let’s take a closer look at how you can resolve this issue by either generating types automatically or manually through definition files. Step-by-Step Solution Configuring tsconfig.json Your tsconfig.json file plays a vital role in determining how TypeScript behaves when compiling your library. Below is a basic setup that you might already have configured: { "name": "@mneelansh/test-lib", "private": false, "version": "0.0.2", "scripts": { "dev": "vite", "build": "vue-tsc --noEmit && vite build", "preview": "vite preview" }, "emitDeclarationOnly": true, "declaration": true, "main": "./dist/lib.umd.js", "module": "./dist/lib.es.js", "types": "./dist/main.d.ts", "exports": { ".": { "import": "./dist/lib.es.js", "require": "./dist/lib.umd.js" }, "./dist/style.css": "./dist/style.css" }, "files": [ "dist" ], "dependencies": { "@types/node": "^17.0.25", "vue": "^3.2.25" }, "devDependencies": { "@vitejs/plugin-vue": "^2.3.1", "typescript": "^4.5.4", "vite": "^2.9.5", "vue-tsc": "^0.34.7" } } In the above configuration, ensure that the properties emitDeclarationOnly and declaration are set to true. This instructs TypeScript to only emit type declaration files for your library without generating JavaScript files. Adding Type Definitions If you confirm that your tsconfig.json is configured correctly, you should focus on your Vite configuration. Here’s an example of how your vite.config.ts could look: import { defineConfig } from "vite"; import vue from "@vitejs/plugin-vue"; const path = require("path"); export default defineConfig({ build: { lib: { entry: path.resolve(__dirname, "src/index.ts"), name: "Button", fileName: (format) => `lib.${format}.js`, }, rollupOptions: { external: ["vue"], output: { globals: { vue: "Vue", }, }, }, }, plugins: [vue()], }); Ensure that the entry point correctly points to your main TypeScript file where your components are exported. Vite will generate a lib structure in the dist folder based on this. Generating Types Automatically If your components are exported properly and you are still not seeing types in the final build, you might need to handle generating .d.ts files manually. You can do this by creating a index.d.ts file in your src directory with the following structure: // index.d.ts declare module "your-module-name" { export interface YourComponentProps { // Define your props here } export class YourComponent { constructor(props: YourComponentProps); // More methods or properties can be added here } } Make sure the name of the module matches the import statements of the components in your project. Building the Library Once you have updated your configurations and defined your types, you can build the library by running the following command: npm run build This should generate your library files along with the necessary type definitions in the dist directory. Frequently Asked Questions Q: Why aren’t my types being generated? A: Ensure that emitDeclarationOnly and declaration are set to true in your tsconfig.json. Also, double-check that your entry point in vite.config.ts is correctly pointing to your components. Q: Can I manually create type definitions? A: Yes, creating a custom index.d.ts file can help include types that TypeScript might not infer automatically from your components. Q: Do I need to publish my types separately? A: No, if your build process is set up correctly, the types will be included automatically in the generated packages in the dist folder. Conclusion Following the steps outlined above should help you successfully include TypeScript types in your Vite library build. By configuring tsconfig.json, your Vite configuration, and possibly adding manual type definitions, you can ensure your component library is fully typed, providing a better development experience for users consuming your library.

May 10, 2025 - 21:11

How to Add TypeScript Types in Vite Library Mode

Introduction

When building a component library with Vite and Vue.js, it's essential to ensure that your TypeScript types are included in the final build. If you've followed the Vite documentation for library mode and defined props and interfaces in your components but find that types are missing from the final output, this article will guide you through the necessary steps to include those types.

Understanding the Issue

The common challenge faced when building libraries using Vite is ensuring that TypeScript type definitions are generated and included. This can happen for various reasons, including misconfigurations in your tsconfig.json file or missing options in your Vite configuration.

Let’s take a closer look at how you can resolve this issue by either generating types automatically or manually through definition files.

Step-by-Step Solution

Configuring `tsconfig.json`

Your tsconfig.json file plays a vital role in determining how TypeScript behaves when compiling your library. Below is a basic setup that you might already have configured:

{
  "name": "@mneelansh/test-lib",
  "private": false,
  "version": "0.0.2",
  "scripts": {
    "dev": "vite",
    "build": "vue-tsc --noEmit && vite build",
    "preview": "vite preview"
  },
  "emitDeclarationOnly": true,
  "declaration": true,
  "main": "./dist/lib.umd.js",
  "module": "./dist/lib.es.js",
  "types": "./dist/main.d.ts",
  "exports": {
    ".": {
      "import": "./dist/lib.es.js",
      "require": "./dist/lib.umd.js"
    },
    "./dist/style.css": "./dist/style.css"
  },
  "files": [ "dist" ],
  "dependencies": {
    "@types/node": "^17.0.25",
    "vue": "^3.2.25"
  },
  "devDependencies": {
    "@vitejs/plugin-vue": "^2.3.1",
    "typescript": "^4.5.4",
    "vite": "^2.9.5",
    "vue-tsc": "^0.34.7"
  }
}

In the above configuration, ensure that the properties emitDeclarationOnly and declaration are set to true. This instructs TypeScript to only emit type declaration files for your library without generating JavaScript files.

Adding Type Definitions

If you confirm that your tsconfig.json is configured correctly, you should focus on your Vite configuration. Here’s an example of how your vite.config.ts could look:

import { defineConfig } from "vite";
import vue from "@vitejs/plugin-vue";

const path = require("path");

export default defineConfig({
  build: {
    lib: {
      entry: path.resolve(__dirname, "src/index.ts"),
      name: "Button",
      fileName: (format) => `lib.${format}.js`,
    },
    rollupOptions: {
      external: ["vue"],
      output: {
        globals: {
          vue: "Vue",
        },
      },
    },
  },
  plugins: [vue()],
});

Ensure that the entry point correctly points to your main TypeScript file where your components are exported. Vite will generate a lib structure in the dist folder based on this.

Generating Types Automatically

If your components are exported properly and you are still not seeing types in the final build, you might need to handle generating .d.ts files manually. You can do this by creating a index.d.ts file in your src directory with the following structure:

// index.d.ts
declare module "your-module-name" {
  export interface YourComponentProps {
    // Define your props here
  }

  export class YourComponent {
    constructor(props: YourComponentProps);
    // More methods or properties can be added here
  }
}

Make sure the name of the module matches the import statements of the components in your project.

Building the Library

Once you have updated your configurations and defined your types, you can build the library by running the following command:

npm run build

This should generate your library files along with the necessary type definitions in the dist directory.

Frequently Asked Questions

Q: Why aren’t my types being generated?
A: Ensure that emitDeclarationOnly and declaration are set to true in your tsconfig.json. Also, double-check that your entry point in vite.config.ts is correctly pointing to your components.

Q: Can I manually create type definitions?
A: Yes, creating a custom index.d.ts file can help include types that TypeScript might not infer automatically from your components.

Q: Do I need to publish my types separately?
A: No, if your build process is set up correctly, the types will be included automatically in the generated packages in the dist folder.

Conclusion

Following the steps outlined above should help you successfully include TypeScript types in your Vite library build. By configuring tsconfig.json, your Vite configuration, and possibly adding manual type definitions, you can ensure your component library is fully typed, providing a better development experience for users consuming your library.