Add JSDoc comments

deno.json

@@ -1,6 +1,6 @@
 {
   "name": "@vrugtehagel/eleventy-document-outline",
-  "version": "0.0.2",
+  "version": "0.0.3",
   "exports": "./mod.ts",
   "publish": {
     "include": ["mod.ts", "README.md"]

mod.ts

@@ -1,35 +1,49 @@
 import * as HTMLParser from "npm:node-html-parser@^6.1";
 
+/** Allowed header tag names, lowercased */
 const HEADERS: string[] = ["h1", "h2", "h3", "h4", "h5", "h6", "h7"] as const;
+/** Default options, used if not provided explicitly */
 const DEFAULTS: EleventyDocumentOutlineOptions = {
   headers: ["h1", "h2", "h3"],
   output: ({ id, text, header }) =>
     `<a href="#${id}" class="link-${header}">${text}</a>`,
 };
 
+/** The Eleventy config object, should be a better type than "any" but alas */
 type EleventyConfig = any;
+/** UUIDs are rendered by the shortcode and then replaced in a transform at build time */
 type UUID = string;
+/** Allowed header tag names, lowercased, as a type */
 type LowerCaseHeader = typeof HEADERS[number];
+/** Allowed header tag names, uppercased */
 type UpperCaseHeader = "H1" | "H2" | "H3" | "H4" | "H5" | "H6" | "H7";
+/** Allowed header tag names, case-insensitive */
 type Header = LowerCaseHeader | UpperCaseHeader;
+/** The options. All fields are optional through Partial<…> */
 type EleventyDocumentOutlineOptions = {
   headers: Header[];
   output: (info: { id: string; text: string; header: Header }) => string;
 };
 
+/**
+ * Receives a user-provided header and returns a normalized (lowercased) header.
+ * Throws if the argument is not a valid header.
+ */
 function normalize(header: string): LowerCaseHeader {
   const lowerCase = header.toLowerCase();
   if (HEADERS.includes(lowerCase)) return lowerCase;
   throw new Error(`Invalid header "${header}" found.`);
 }
 
+/** The plugin itself, with an optional options object as second argument. */
 export default function EleventyDocumentOutline(
   config: EleventyConfig,
-  options: Partial<EleventyDocumentOutlineOptions> = {},
+  options?: Partial<EleventyDocumentOutlineOptions> = {},
 ) {
   const normalizedOptions = Object.assign({}, DEFAULTS, options);
   const memory = new Map<UUID, LowerCaseHeader[]>();
 
+  /** The {% outline %} shortcode, with optional configurable headers */
   config.addShortcode("outline", function (...headers: Header[]) {
     const uuid = crypto.randomUUID();
     const normalized = headers.length == 0
@@ -39,6 +53,7 @@ export default function EleventyDocumentOutline(
     return uuid;
   });
 
+  /** The transform responsible for actually generating and rendering the links */
   config.addTransform(
     "document-outline",
     async function (this: any, content: string) {