Overview

Revisionist is a simple tool to help you manage versions of content in your web application. Everytime your data changes, you can save it as a revision in a Revisionist instance. You can then access the last x versions of your content (10 by default).

Revisionist is open source. View the annotated source code.

Get it

Through Bower

bower install revisionist

Through NPM

npm install revisionist

How to use it

In a <script> tag

Include the script in your page. A global "Revisionist" variable will be made available.

rev = new window.Revisionist()

With an AMD loader

Using an AMD loader such as RequireJS:

require(['path/to/revisionist'], function(Revisionist) {
  rev = new Revisionist()
});

In Node

Revisionist = require('path/to/revisionist')
rev = new Revisionist()

API

Any instance has these two methods available:

change(newValue)

Creates a new revision. It returns the same value you passed in

rev.change('bananas')
// -> 'bananas'

recover(version)

Recovers a previous version of your content and returns it.

rev.change('tomatoes')

rev.recover(0)
// -> 'bananas'

rev.recover(1)
// -> 'tomatoes'

Options

When creating a Revisionist instance, you can pass it an options hash to change the default behaviour. The available options are:

versions | Number

The maximum number of revisions you wish to store. Defaults to 10.

plugin | String

The plugin you wish to use with this instance. The plugin must have been registered before using the class method registerPlugin

Plugin Architecture

Revisionist uses a plugin architecture, so you can wrap around it's two main functions, change and recover to implement your own logic.

The "Simple" plugin shipped by default simply stores and returns the values as they're passed in.

Authoring a plugin

To write a plugin, all you really have to do is provide Revisionist with a hash containing two methods:

change(newValue)

This method will be called by the Revisionist instance when you do instance.change("bananas"). In this case, your implementation of change would receive an argument with a value of bananas.

recover(oldValue)

This method will be called by the Revisionist instance when you do instance.recover(2). Your implementation of recover gets an argument with the value previously stored as revision #2.

Both of these methods are executed in the context of your own plugin.

Registering and Unregistering a plugin

The Revisionist class exposes a class method to register your plugins.

registerPlugin(name, hash)

Registers a plugin with a name and a hash containing change and recover functions. If your plugin does not follow this naming convention, it will not work properly.

Example:

MyPlugin = {
  change: function(newValue) {},
  recover: function(oldValue) {}
}

Revisionist.registerPlugin('myPlugin', MyPlugin);

unregisterPlugin(name)

Unregisters a plugin with a given name.

Example:

Revisionist.unregisterPlugin('myPlugin')
// MyPlugin is not available anymore