TrackedJSON

TrackedJSON provides frictionless undo/redo for JSON objects.

TrackedJSON tries to maintain a relatively minimal API - the core of the library is the .data property which represents the JSON object you want to keep track of. You can update it just like a regular JavaScript object, with the only requirement being that properties have to be valid JSON types.

Install

npm install tracked-json

Basic Usage

You can use it like so:

const tracked = new TrackedJSON();

// tracked.data is an empty object at this point

tracked.data.value = 1;
tracked.data.value = 2;
tracked.data.value = 3;

tracked.undo();
tracked.undo();

// tracked.data.value === 1

tracked.redo();
tracked.redo();

// tracked.data.value === 3

How many undo/redo operations are there for my data object?

You can get the size of the undo stack using undoSize like so:

const tracked = new TrackedJSON({ initialState: { value: 0 } });
tracked.data.value = 1;
tracked.data.value = 2;
console.log(tracked.undoSize); // 2
tracked.undo();
tracked.undo();
console.log(tracked.redoSize); // 2

Instantiate with a given state

You can instantiate an object with a starting state like so:

const tracked = new TrackedJSON({ initialState: { value: 0 } });
console.log(tracked.data.value); // 0

Replacing the whole data object

If you want to replace the whole data object, this is possible and will be tracked as normal, like so:

const tracked = new TrackedJSON();
tracked.data.value = 0;
tracked.data = { value: 1 };
tracked.undo();
console.log(tracked.data.value); // 0

Guards against non JSON properties

Properties and nested properties of the data object must be valid JSON and will throw an error if not:

const tracked = new TrackedJSON();
tracked.data.value = new Map(); // throws error
tracked.data.value = {}; // does not throw error

License

MIT