feat: add type definitions

Closes #17

Author: rexxars

package.json

@@ -16,11 +16,24 @@
   "author": "Espen Hovlandsdal <[email protected]>",
   "type": "module",
   "main": "./src/Lowlight.js",
+  "types": "./src/Lowlight.d.ts",
   "module": "./src/Lowlight.js",
   "exports": {
-    ".": "./src/Lowlight.js",
-    "./common": "./src/common.js",
-    "./all": "./src/all.js"
+    ".": {
+      "types": "./src/Lowlight.d.ts",
+      "import": "./src/Lowlight.js",
+      "default": "./src/Lowlight.js"
+    },
+    "./common": {
+      "types": "./src/common.d.ts",
+      "import": "./src/common.js",
+      "default": "./src/common.js"
+    },
+    "./all": {
+      "types": "./src/all.d.ts",
+      "import": "./src/all.js",
+      "default": "./src/all.js"
+    }
   },
   "files": [
     "src"

src/Lowlight.d.ts

@@ -0,0 +1,20 @@
+interface LowlightMarker {
+    line: number;
+    className?: number;
+}
+interface LowlightProps {
+    className?: string;
+    language?: string;
+    value: string;
+    prefix?: string;
+    subset?: string[];
+    inline?: boolean;
+    markers: number[] | LowlightMarker[];
+}
+declare function Lowlight(props: LowlightProps): JSX.Element;
+declare namespace Lowlight {
+    var displayName: string;
+    var registerLanguage: (language: string, syntax: any) => void;
+    var hasLanguage: (lang: string) => boolean;
+}
+export default Lowlight;

src/all.d.ts

@@ -0,0 +1,2 @@
+declare const _default: {};
+export default _default;

src/common.d.ts

@@ -0,0 +1,2 @@
+declare const _default: {};
+export default _default;