Add typescript definitions for Article and ReadabilityOptions objects. (mozilla#971)

* Add typescript definitions for Article and ReadabilityOptions objects.

* fix: improve TypeScript type definition

* removed non-existing attributes in ReadabilityOptions
* use ReadabilityOptions in the Readability definition
* add missing attributes
* add explanatory commentary for all attributes of ReadabilityOptions

* fix: remove unused `url` attribute of the ReadabilityOptions type

* fix: callbacks doesn’t exist either

Author: mcepl

index.d.ts

@@ -1,6 +1,6 @@
 /**
  * Decides whether or not the document is reader-able without parsing the whole thing.
- * @return {boolean} Whether or not we suspect Readability.parse() will suceeed at returning an article object.
+ * @return {boolean} Whether or not we suspect Readability.parse() will succeed at returning an article object.
  */
 export function isProbablyReaderable(
   document: Document,
@@ -14,20 +14,72 @@ export function isProbablyReaderable(
   }
 ): boolean;
 
+export interface ReadabilityOptions {
+  /**
+   * Whether to output debug messages. Defaults to `false`.
+   */
+  debug?: boolean;
+  /**
+   * The maximum number of elements to parse. If the document exceeds this,
+   * Readability will stop processing. Useful for performance on very large documents.
+   * Defaults to 0 (no limit).
+   */
+  maxElemsToParse?: number;
+  /**
+   * The number of top candidate nodes to consider when determining the main article content.
+   * A higher number might lead to better results but could increase processing time.
+   * Defaults to 5.
+   */
+  nbTopCandidates?: number;
+  /**
+   * The minimum number of characters required for a text node to be considered
+   * significant and included in the article content.
+   * Defaults to 500.
+   */
+  charThreshold?: number;
+  /**
+   * An array of class names to preserve. If `keepClasses` is `true`,
+   * only classes in this array will be kept. Defaults to an empty array.
+   */
+  classesToPreserve?: string[];
+  /**
+   * If `true`, Readability will retain the original class names of elements
+   * in the parsed article content. If `classesToPreserve` is also set,
+   * only those specified classes will be kept. Defaults to `false`.
+   */
+  keepClasses?: boolean;
+  /**
+   * A function that serializes an HTML element into a string.
+   * Defaults to `el => el.innerHTML`. This is used to get the content
+   * of the parsed article.
+   * @param el The Node to serialize.
+   * @returns The HTML string representation of the element's content.
+   */
+  serializer?: (el: Node) => string;
+  /**
+   * If `true`, Readability will not attempt to parse or extract
+   * JSON-LD structured data from the document. Defaults to `false`.
+   */
+  disableJSONLD?: boolean;
+  /**
+   * A regular expression used to validate video URLs. Only videos
+   * matching this regex will be included in the parsed content.
+   * Defaults to a regex that allows common video embedding platforms.
+   */
+  allowedVideoRegex?: RegExp;
+  /**
+   * A modifier applied to the link density score of an element.
+   * This influences how Readability judges the main content area,
+   * potentially helping with documents that have many or few links.
+   * Defaults to 1.
+   */
+  linkDensityModifier?: number;
+}
+
 export class Readability<T = string> {
   constructor(
     document: Document,
-    options?: {
-      debug?: boolean;
-      maxElemsToParse?: number;
-      nbTopCandidates?: number;
-      charThreshold?: number;
-      classesToPreserve?: string[];
-      keepClasses?: boolean;
-      serializer?: (node: Node) => T;
-      disableJSONLD?: boolean;
-      allowedVideoRegex?: RegExp;
-    }
+    options?: ReadabilityOptions
   );
 
   parse(): null | {
@@ -62,3 +114,7 @@ export class Readability<T = string> {
     publishedTime: string | null | undefined;
   };
 }
+
+// Assuming Article is the return type of Readability.prototype.parse()
+export type Article = ReturnType<Readability['parse']>;
+