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JSON Pointer

This is an implementation of RFC-6901 JSON Pointer. JSON Pointer is designed for referring to data values within a JSON document. It's designed to be URL friendly so it can be used as a URL fragment that points to a specific part of the JSON document.

Installation

Includes support for node.js (ES Modules, TypeScript) and browsers.

npm install @hyperjump/json-pointer

Usage

import * as JsonPointer from "@hyperjump/json-pointer";

const value = {
  "foo": {
    "bar": 42
  }
};

// Construct pointers
const fooPointer = JsonPointer.append("foo", JsonPointer.nil); // "/foo"
const fooBarPointer = JsonPointer.append(fooPointer, "bar"); // "/foo/bar"

// Get a value from a pointer
const getFooBar = JsonPointer.get(fooBarPointer);
getFooBar(value); // 42

// Set a value from a pointer
// New value is returned without modifying the original
const setFooBar = JsonPointer.set(fooBarPointer);
setFooBar(value, 33); // { "foo": { "bar": 33 } }

// Assign a value from a pointer
// The original value is changed and no value is returned
const assignFooBar = JsonPointer.assign(fooBarPointer);
assignFooBar(value, 33); // { "foo": { "bar": 33 } }

// Unset a value from a pointer
// New value is returned without modifying the original
const unsetFooBar = JsonPointer.unset(fooBarPointer);
setFooBar(value); // { "foo": {} }

// Delete a value from a pointer
// The original value is changed and no value is returned
const deleteFooBar = JsonPointer.remove(fooBarPointer);
deleteFooBar(value); // { "foo": {} }

API

  • nil: ""

    The empty pointer.

  • pointerSegments: (pointer: string) => Generator<string>

    An iterator for the segments of a JSON Pointer that handles escaping.

  • append: (segment: string, pointer: string) => string

    Append a segment to a JSON Pointer.

  • get: (pointer: string, subject: any) => any

    Use a JSON Pointer to get a value. This function can be curried.

  • set: (pointer: string, subject: any, value: any) => any

    Immutably set a value using a JSON Pointer. Returns a new version of subject with the value set. The original subject is not changed, but the value isn't entirely cloned. Values that aren't changed will point to the same value as the original. This function can be curried.

  • assign: (pointer: string, subject: any, value: any) => void

    Mutate a value using a JSON Pointer. This function can be curried.

  • unset: (pointer: string, subject: any) => any

    Immutably delete a value using a JSON Pointer. Returns a new version of subject without the value. The original subject is not changed, but the value isn't entirely cloned. Values that aren't changed will point to the same value as the original. This function can be curried.

  • remove: (pointer: string, subject: any) => void

    Delete a value using a JSON Pointer. This function can be curried.

Contributing

Tests

Run the tests

npm test

Run the tests with a continuous test runner

npm test -- --watch