Add TypeScript declaration bundle output

docs/README.md

@@ -7,6 +7,7 @@ Delightful library bundler.
 - 🚀 Fast, zero-config by default.
 - 📦 Using Rollup under the hood.
 - 🚗 Automatically transforms JS files using Buble, Babel or TypeScript.
+- 🧩 Bundles TypeScript declarations into a single `.d.ts` file.
 - 💅 Built-in support for CSS, Sass, Stylus, Less and CSS modules.
 - 🎶 Ridiculously easy to use Rollup plugins if you want.
 - 🚨 Friendly error logging experience.
@@ -35,3 +36,9 @@ And you want minified bundles?
 ```bash
 bili --format esm-min --format cjs-min
 ```
+
+Bundle TypeScript declarations too:
+
+```bash
+bili src/index.ts --dts
+```

docs/recipes/javascript.md

@@ -22,7 +22,7 @@ module.exports = {
   presets: ['bili/babel'],
   plugins: [
     // Add your babel plugins...
-  ]
+  ],
 }
 ```
 
@@ -53,6 +53,23 @@ We automatically use [rollup-plugin-typescript2](https://github.com/ezolenko/rol
 yarn add typescript rollup-plugin-typescript2 --dev
 ```
 
+Bili can also bundle emitted declarations into one `.d.ts` entry file:
+
+```bash
+bili src/index.ts --dts
+```
+
+Or choose the declaration bundle file name:
+
+```js
+// bili.config.js
+module.exports = {
+  output: {
+    dts: 'index.d.ts',
+  },
+}
+```
+
 ## Use Babel with TypeScript
 
 By default Babel is also used for `.ts` files, it will process the file after TypeScript. It's recommended to set `compilerOptions.target` to `es2017` or above in `tsconfig.json` and let Babel transform the code to ES5 instead. If you want to disable Babel, set `plugins: { babel: false }` in your Bili config file.

package.json

@@ -48,6 +48,7 @@
     "chalk": "^4.1.0",
     "ora": "^4.0.4",
     "rollup": "^2.16.1",
+    "rollup-plugin-dts": "1.3.0",
     "rollup-plugin-hashbang": "^2.2.2",
     "rollup-plugin-postcss": "^3.1.2",
     "rollup-plugin-terser": "^6.1.0",

src/cli.ts

@@ -47,6 +47,10 @@ cli
     '--no-map',
     'Disable source maps, enabled by default for minified bundles'
   )
+  .option(
+    '--dts [fileName]',
+    'Bundle TypeScript declarations into a single .d.ts file'
+  )
   .option('--map-exclude-sources', 'Exclude source code in source maps')
   .option('--no-async-pro, --no-async-to-promises', 'Leave async/await as is')
   .option('--concurrent', 'Build concurrently')
@@ -70,6 +74,7 @@ cli
           minify: options.minify,
           extractCSS: options.extractCss,
           sourceMap: options.map,
+          dts: options.dts,
           sourceMapExcludeSources: options.mapExcludeSources,
           target: options.target,
         },