Install

To install the package, run the following command:

npm install @hyperjump/json-pointer

The package is an ES module with no dependencies, and it works the same in Node.js and browsers. Import the functions that you use:

import { pointerGet, pointerSet } from "@hyperjump/json-pointer";

TypeScript

The package includes its type declarations. Besides the functions, it exports types for JSON values. It also exports types for the functions that pointerGet, pointerSet, pointerAssign, pointerUnset, and pointerRemove return when you give them only a pointer. For more information about those functions, see Apply a pointer many times.

The package exports the following types:

Type	Description
`Json`	Any JSON value: a string, number, boolean, null, object, or array
`JsonObject`	A JSON object
`ReadonlyJson`	A readonly JSON value, like one declared `as const`
`ReadonlyJsonObject`	A readonly JSON object
`PointerSegments`	A pointer’s unescaped segments: `readonly string[]`
`Pointer`	A pointer as a string, or its `PointerSegments`
`PointerGetter`	The function that `pointerGet(pointer)` returns
`PointerSetter`	The function that `pointerSet(pointer)` returns
`PointerAssigner`	The function that `pointerAssign(pointer)` returns: `(subject: Json, value: Json) => void`
`PointerUnsetter`	The function that `pointerUnset(pointer)` returns
`PointerRemover`	The function that `pointerRemove(pointer)` returns: `(subject: Json) => void`

For example, a PointerGetter can type a function that you pass to map:

import { pointerGet } from "@hyperjump/json-pointer";
import type { Json, PointerGetter } from "@hyperjump/json-pointer";

const getName: PointerGetter = pointerGet("/name");
const people: Json[] = [{ name: "Ada" }, { name: "Grace" }];
people.map(getName); // ["Ada", "Grace"]

Readonly values

pointerGet, pointerSet, and pointerUnset don’t change their subject, so they accept a ReadonlyJson. When the subject is readonly, so is the value that they return. pointerAssign and pointerRemove change their subject, so they accept only a Json:

const doc = { name: "Ada", languages: ["English"] } as const;

pointerGet("/languages", doc); // ReadonlyJson | undefined
pointerAssign("/name", doc, "Grace"); // type error