ShadowJson

A small utility class that helps to generate path-specific and manageable JSON object copy

Why

In many dev cases, we have to keep an original JSON object while having another deep copied object for editing. Simply deep copying the whole object can lead to unnecessary memory usage and hard management with the original data. ShadowJson solves these problems by following features:

1. allow path-specific clone
2. easy commit/discard changes
3. small implementation (476 bytes)
4. support CJS, ESM and UMD

Install

npm install --save ShadowJson

Usage

const ShadowJson = require('ShadowJson');

let source = { a: 1, b: '2', c: { d: 5 } };

// create ShadowJson with initial path 'c'
let shadow = new ShadowJson(source, ['c']);

// edit the shadow copy
// modify path 'c.d'
shadow.set('c.d', {x: 7});

// delete path 'b'
shadow.set('b', undefined);

// add path 'z'
shadow.set('z', 3);

// change to path 'b' is discarded
shadow.discard('b');

// commit the rest of the changes
shadow.commit();

console.log(source); // { a: 1, b: '2', c: { d: { x: 7 } }, z: 3 }

API

ShadowJson(obj, paths)

The ShadowJson constructor. Returns Object.

Name | Type | Description --- | --- | --- obj | Object | Required.The JSON Object used as the source data. paths | Array<String> | The paths need to be copied.

Note: Avoid using '.' or '' as object keys in the source data.

get(path)

Get the value of a copied path. Returns Any.

Name | Type | Description --- | --- | --- path | String | return an Object of all copied path and value pairs if this param is not provided.

set(path, val)

Set the value of a path. Returns void.

Name | Type | Description --- | --- | --- path | String | Required.The path to be set. val | Any | The path will be set to undefined if this param is not provided.

commit(path)

Commit the changes to the source data. Returns void.

Name | Type | Description --- | --- | --- path | String | Commit all changes if this param is not provided.

Note: If changes are made to a path and its subpath, the most recent path change will override.

discard(path)

Discard changes made to ShadowObject. Returns void.

Name | Type | Description --- | --- | --- path | String | Discard all changes if this param is not provided.

License

MIT