JSON Undo

JSON Undo is a lightweight library for tracking changes in JSON objects with undo and redo functionality. It is designed for memory-sensitive applications by efficiently managing changes without duplicating entire objects.

Installation

npm install json-undo

Usage

Example 1: Basic Usage with Undo and Redo

const JSONChangesTracker = require('json-undo');

const original = { name: "Alice", age: 25 };
const tracker = new JSONChangesTracker(original);

console.log(tracker.get()); 
// Output: { name: "Alice", age: 25 }

original.name = "Bob"; 
tracker.update(original); 

console.log(tracker.get()); 
// Output: { name: "Bob", age: 25 }

original.age = 26; 
tracker.update(original);

console.log(tracker.get()); 
// Output: { name: "Bob", age: 26 }

// Undo the last change
tracker.undo();
console.log(tracker.get()); 
// Output: { name: "Bob", age: 25 }

// Redo the undone change
tracker.redo();
console.log(tracker.get()); 
// Output: { name: "Bob", age: 26 }

Example 2: Complex JSON Object with Nested Changes

const JSONChangesTracker = require('json-undo');

const original = { 
  user: { name: "Charlie", details: { age: 30, city: "New York" } }, 
  active: true 
};

const tracker = new JSONChangesTracker(original);

console.log(tracker.get()); 
// Output: { user: { name: "Charlie", details: { age: 30, city: "New York" } }, active: true }

original.user.name = "David"; 
tracker.update(original);

console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "New York" } }, active: true }

original.user.details.city = "San Francisco"; 
tracker.update(original);

console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "San Francisco" } }, active: true }

original.active = false; 
tracker.update(original);

console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "San Francisco" } }, active: false }

// Undo all changes
tracker.undo();
console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "New York" } }, active: true }

tracker.undo();
console.log(tracker.get()); 
// Output: { user: { name: "Charlie", details: { age: 30, city: "New York" } }, active: true }

// Redo the last undo
tracker.redo();
console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "New York" } }, active: true }

tracker.redo();
console.log(tracker.get()); 
// Output: { user: { name: "David", details: { age: 30, city: "San Francisco" } }, active: true }

Example 3: Checking if Undo/Redo is Possible

const JSONChangesTracker = require('json-undo');

const original = { item: "Laptop", price: 1000 };
const tracker = new JSONChangesTracker(original);

console.log(tracker.canUndo()); // Output: false (No changes yet)
console.log(tracker.canRedo()); // Output: false (No undone changes)

original.price = 1200; 
tracker.update(original);
console.log(tracker.get()); // Output: { item: "Laptop", price: 1200 }

console.log(tracker.canUndo()); // Output: true (Undo possible)
console.log(tracker.canRedo()); // Output: false (No redo yet)

tracker.undo();
console.log(tracker.get()); // Output: { item: "Laptop", price: 1000 }

console.log(tracker.canUndo()); // Output: false (No more undo)
console.log(tracker.canRedo()); // Output: true (Redo possible)

tracker.redo();
console.log(tracker.get()); // Output: { item: "Laptop", price: 1200 }

Features

• Track JSON object changes.
• Undo and redo functionality.
• Memory-efficient change tracking.
• Suitable for large objects.

API

new JSONChangesTracker(initialJson: object)

Creates an instance of JSONChangesTracker.

update(updatedJson: object)

Tracks the changes in the provided JSON object.

undo(): object

Reverts the JSON object to the previous state.

redo(): object

Restores the JSON object to the state before the undo.

get(): object

Returns the current state of the JSON object.

canUndo(): boolean

Returns true if there is a history of changes to undo.

canRedo(): boolean

Returns true if there are undone changes to redo.

License

This project is licensed under the MIT License.

Author

Manish Gun

• GitHub
• Website