undore

Undore

A persistent data structure to manage undos and redos

Example

var undore = require('undore');

// initialize the state to 10
var dataState = undore(10);

// operations does not mutate the original object
undore.set(dataState, 5);
console.log(undore.get(dataState)); // 10

// but we can manually reasign our variable
dataState = undore.set(dataState, 5);
console.log(undore.get(dataState)); // 5

// maybe 5 isn't really a nice value, let's rollback
dataState = undore.undo(dataState);
console.log(undore.get(dataState)); // 10

// nevermind, 5 is pretty awesome
dataState = undore.redo(dataState);
console.log(undore.get(dataState)); // 5

Operations

undore(initialState) → undore

Constructor of an Undore instance. This instance is in fact an instance of Immutable.Map with three keys:

• state: The most recent and valid version of the state
• history: An Immutable.Stack that contains every past versions of the state.
• redos: Also an Immutable.Stack with changes that were undone and may be redone.

Note: Undore does not enforce the use of immutable object as its state.

undore.set(undore, value) → undore

Change the value and record the change in the history.

undore.get(undore) → value

Get the current value.

undore.update(undore, updater) → undore

Update the state with a function of previous state to next state. These are equivalent:

undore.set(myState, updater(undore.get(myState)))
undore.update(myState, updater)

undore.undo(undore) → undore

Undo the latest change if any.

undore.redo(undore) → undore

Redo the latest undo if any.

Demo

• undore-react-example

License

MIT