fix: add TS declarations (#282)

Author: DamianoMagrini

index.d.ts

@@ -0,0 +1,36 @@
+declare module 'extract-css-chunks-webpack-plugin' {
+  import { ChunkData, Loader, Plugin } from 'webpack';
+
+  class ExtractCssChunksPlugin extends Plugin {
+    static loader: Loader;
+
+    constructor(options?: ExtractCssChunksPlugin.PluginOptions);
+  }
+
+  namespace ExtractCssChunksPlugin {
+    interface PluginOptions {
+      /**
+       * The filename of the entry chunk.
+       */
+      filename?: string;
+      /**
+       * The filename of non-entry chunks.
+       */
+      chunkFilename?: string;
+      /**
+       * Generates a file name (or template) based on chunk data.
+       */
+      moduleFilename?: (chunk: ChunkData) => string;
+      /**
+       * Remove warnings about conflicting order.
+       */
+      ignoreOrder?: boolean;
+      /**
+       * Inserts `<link>` at the given position (https://github.com/faceyspacey/extract-css-chunks-webpack-pluginn#insert).
+       */
+      insert?: string | Function;
+    }
+  }
+
+  export = ExtractCssChunksPlugin;
+}

package.json

@@ -31,6 +31,7 @@
     "extract-css-chunks-webpack-plugin"
   ],
   "main": "dist/cjs.js",
+  "types": "index.d.ts",
   "engines": {
     "node": ">= 6.9.0"
   },
@@ -59,7 +60,8 @@
     "travis": "npm run ci:coverage"
   },
   "files": [
-    "dist"
+    "dist",
+    "index.d.ts"
   ],
   "peerDependencies": {
     "webpack": "^4.4.0 || ^5.0.0"