Json Pointer

This is a json-pointer implementation following RFC 6901. As the error handling is not further specified, this implementation will return undefined for any invalid pointer/missing data, making it very handy to check uncertain data, i.e.

const data = {};
if (pointer.get(data, "/path/to/nested/item") !== undefined) {
    // value is set, do something
}

// instead of
if (data.path && data.path.to && data.path.to.nested && data.path.to.nested.item) {
    // value is set, do something
}

install with npm i gson-pointer --save

Besides the standard get function, this library offers additional functions to work with json-pointer

method	description
get (data, pointer) -> [mixed]	returns the value at given pointer
set (data, pointer, value) -> data	sets the value at the given path
delete (data, pointer) -> data	removes a property from data
join (pointer*) -> pointer	joins multiple pointers to a single one
split (pointer) -> [array]	returns a json-pointer as an array

Usage

pointer.get(data, pointer)

const gp = require("gson-pointer");

const data = {
    parent: {
        child: {
            title: "title of child"
        }
    }
}

const titleOfChild = gp.get(data, "/parent/child/title"); // output: "title of child"
console.log(gp.get(data, "/parent/missing/path")); // output: undefined

pointer.set(data, pointer, value)

set values on an object

const gp = require("gson-pointer");

var data = {
    parent: {
        children: [
            {
                title: "title of child"
            }
        ]
    }
};

pointer.set(data, "#/parent/children/1", {title: "second child"});
console.log(data.parent.children.length); // output: 2

and may create data on its path

const gp = require("gson-pointer");
const data = gp.set({}, "/list/[]/value", 42);
console.log(data); // output: { list: [ { value: 42 } ] }

pointer.delete(data, pointer)

delete properties or array items

const gp = require("gson-pointer");
const data = gp.delete({ parent: { arrayOrObject: [ 0, 1 ] }}, "#/parent/arrayOrObject/1");
console.log(data.parent.arrayOrObject); // output: [0]

pointer.split(pointer)

returns a json-pointer as a list of properties

const gp = require("gson-pointer");
const list = gp.split("#/parent/arrayOrObject/1");
console.log(list); // output: ["parent", "arrayOrObject", "1"]

pointer.join(pointer, pointer, ...)

joins all arguments to a valid json pointer

const gp = require("gson-pointer");
const key = "my key";
console.log(gp.join("root", key, "/to/target")); // output: "/root/my key/to/target"

and joins relative pointers as expected

const gp = require("gson-pointer");
console.log(gp.join("/path/to/value", "../object")); // output: "/path/to/object"

in order to join an array received from split, you can use join.list() to retrieve a valid pointer

const gp = require("gson-pointer");
const list = gp.split("/my/path/to/child");
list.pop();
console.log(gp.join.list(list)); // output: "/my/path/to"

Fragment identifier

All methods support a leading uri fragment identifier (#), which will ensure that property-values are uri decoded when resolving the path within data and also ensure that any pointer is returned uri encoded with a leading #. e.g.

const gp = require("gson-pointer");

// get
const value = gp.get({ "my value": true }, "#/my%20value");
console.log(value); // output: true

// join
const pointer = gp.join("#/my value/to%20parent", "../to~1child");
console.log(pointer); // output: "#/my%20value/to~1child"

// join an array of properties
const isURI = true;
const uriPointer = gp.join.list(["my value", "to~1child"], isURI);
console.log(uriPointer); // output: "#/my%20value/to~1child"

benurb/json-pointer