lazy-json-undo-redo

LazyJsonUndoRedo 
================

A 'drop in' history handler with automatic undo/redo functionality for nested javascript objects, using ES6 Object.observe() or Polymer shim.

Best for small editor tools.

ES6 Object.observe() is only supported in Chrome 36+ and Nodejs 11.13+ yet, but LJUR is also usable with polymer(observe-js)

####Demo
edit json

edit maze

####Install
``
bower install --save LazyJsonUndoRedo
npm install --save lazy-json-undo-redo
`

####Unit tests
native

with polymer shim

Usage
-----


`javascript

Init
var o = {}, ljur = new LazyJsonUndoRedo(o);

o.a = 1;
ljur.undo();
console.log(o.a); // undefined
ljur.redo();
console.log(o.a); // 1


Flagging
o = {}, ljur = new LazyJsonUndoRedo(o);
//the changes between the start- end endFlag calls will be treated as one step
//in the history
var endFlagId = ljur.startFlag();
o.c = {}
o.c.b = 1
o.c.e = 2
o.f = 4;
ljur.endFlag(endFlagId);
ljur.undo();
console.log(o); //{}
ljur.redo();
console.log(o); //{c: {b: 1, e: 2}, f: 4}

//or wrap a function between flags:
var changerFn = ljur.wrap(function () {/do changes on o/});
changerFn();//all changes are reversible with one undo() call


Force save
//fast changes can be merged by the api (specially if you're using shim)
o = {}, ljur = new LazyJsonUndoRedo(o);
o.g = {};
o.g.h = 1;
ljur.undo();
console.log(o); //{}

//to avoid this, you can force the history save with ljur.rec()
o.i = {};
ljur.rec();
o.i.j = 2;
ljur.undo();
console.log(o); // {i: {}}


Use whitelists
//if you want to specify witch properties should be listened on an object,
// you can use whitelists:
o = {};
ljur = new LazyJsonUndoRedo();
ljur.setWhiteList(o, ['a', 'b']);
ljur.observeTree(o);//you have to set the whitelist before start to observe the object
o.a = 7; //will be undoable
o.c = 8; //won't be undoable, because 'c' is not on the whitelist
ljur.undo();
console.log(o); // {c: 8}

ljur.getWhitelist(o); //['a', 'b']
ljur.removeWhiteList(o);//whitelists are removable


Use blacklists
//works the same as whitelists
ljur.setBlacklist(object, blacklistedKeys);
ljur.removeBlacklist(object);


Use global black- and whitelist
//you can use this two list for all of the objects added to ljur
ljur.addToGlobalWhitelist('a', 'b', 'x', 'd', 'e');
ljur.removeFromGlobalWhitelist('e', 'x');
ljur.addToGlobalBlacklist('a', 'b', 'x', 'd', 'e');
ljur.removeFromGlobalBlacklist('e', 'x');

Listen to more objects
ljur.observeTree(o2);
ljur.observeTree(o3);


Check support
LazyJsonUndoRedo.checkSupport();//true is native Object.observe() or Polymer is present
ljur.usingShim;//true if it's usin Polymer shim

``