js-undoable

A primitive class which lets you track changes made to it's typed value.

Notes

This class uses JS native strict equality checking to prevent duplicate change entries. This means that assigning the same value (or class instance) in succession will not count as a change. When exported to a buffer, it tries to create dictionary of unique instances of changed values being tracked, in order to unpack with correct references later on. This project is still under development and might have breaking changes. Don't use in production environment until more testing can be done.

Installation

npm install --save js-undoable

Usage Examples

Including in Typescript:

import { Undoable } from 'js-undoable';

Including in NodeJS:

const { Undoable } = require('js-undoable');

An "undoable" number (in Typescript):

import { Undoable } from 'js-undoable';
 
const undoNum = new Undoable<number>(25);
 
undoNum.current = 26;
undoNum.current = 27;
undoNum.current = 28;
undoNum.current = 55;
 
console.log(undoNum.changeCount === 4);  // true
console.log(undoNum.current     === 55); // true
 
undoNum.undo(2); // returns diffs undone
 
console.log(undoNum.changeCount === 2);  // true
console.log(undoNum.current     === 27); // true

Export and load from Buffer (in Typescript):

import { Undoable } from 'js-undoable';
 
const undoNum = new Undoable<number>(25);
 
undoNum.current = 26;
undoNum.current = 27;
undoNum.current = 28;
undoNum.current = 55;
 
const exported = undoNum.toBuffer();
// exported now contains a Buffer object
 
const imported = Undoable.fromBuffer<number>(exported);
// imported is now almost identitical to undoNum

Commit first change to snapshot (in Typescript):

import { Undoable } from 'js-undoable';
 
const undoNum = new Undoable<number>(25);
 
undoNum.current = 26;
undoNum.current = 27;
 
// replace snapshot with "26" change, "25" is gone forever.
undoNum.commit(1);
 
console.log(undoNum.changeCount === 1);  // true
console.log(undoNum.current     === 27); // true
 
undoNum.undo(1);
 
console.log(undoNum.changeCount === 0);  // true
console.log(undoNum.current     === 26); // true

Credits

Author: Hans Doller <[e-mail]