docs: 📝 update readme for missing pkgs; add JS/TS notes

JavaScript-TypeScript-Notes.md

@@ -0,0 +1,30 @@
+# JavaScript and TypeScript Notes
+
+The following is a type definition for a conversion roundtrip from obj to json to obj.\
+@see {@link https://effectivetypescript.com/2020/04/09/jsonify/}
+
+```ts
+// export type JsonifySimple<T> = T extends { toJSON(): infer U }
+// 	? U
+// 	: T extends object
+// 		? { [k in keyof T]: Jsonify<T[k]> }
+// 		: T;
+
+export type Jsonify<T> = T extends { toJSON: (...args: any) => infer R }
+	? Jsonify<R>
+	: T extends Array<infer I>
+		? Array<Jsonify<I>>
+		: T extends (...args: any) => any
+			? never
+			: T extends object
+				? { [K in keyof T]: K extends string | number ? Jsonify<T[K]> : never }
+				: T;
+```
+
+---
+
+Get the single type of an array type e.g: User[] -> User
+
+```ts
+type GetElementType<T extends any[]> = T extends (infer U)[] ? U : never;
+```

README.md

@@ -21,6 +21,19 @@ be triggered. The function will be called after it stops being called for
 N milliseconds. If `immediate` is passed, trigger the function on the
 leading edge, instead of the trailing.
 
+## FetchHelper
+
+Extracts the content from the body of a Response object either\
+as json (if Content-Type=application/json),\
+as text (if Content-Type=text/*),\
+or as a Blob if all else fails.
+
+## JsonParse
+
+Wrapper around Json.parse() to catch any errors and return a Promise.\
+The synchronous version returns an Object with data and error properties.\
+If the parsing failed the error is set. Otherwise it is undefined.
+
 ## MapValueRange
 
 Maps a value in an input range to an output range.