typesafe-object-paths

Typesafe object

A typescript package allowing for safe nested property access within objects. Also comes with arithmetic types (add, subtract) that were needed to support tuples.

This package includes:

NestedKeyOf

A nested verion of keyof which returns all keys of an object, including nested ones.
Example:

type ExampleType = {a: number, b: [string, number], c: {d: string, e: number}};
const a: NestedKeyOf<ExampleType> = "a" // Okay
const b: NestedKeyOf<ExampleType> = "b.0" // Okay
const c: NestedKeyOf<ExampleType> = "a.0" // Error

PathOf

Given a nested path, returns the type of the object at that path

const g: PathOf<ExampleType, "b.0"> = 0; // Error
const g: PathOf<ExampleType, "b.0"> = "hello"; // Okay
const g: PathOf<ExampleType, "a"> = "hello"; // Error

Get

A nested path getter - given an object and a path, will yield the type of the object and the given path

const obj = {a: {b: {c: "d"}}, e: ["f", "g"], h: ["i"]}
get(obj, "e.0") // "f"

The package requires at least typescript 4.1.