Welcome to TiddlyWiki5, a reboot of TiddlyWiki, the venerable, reusable non-linear personal web notebook first released in 2004. It is a complete interactive wiki that can run from a single HTML file in the browser or as a powerful node.js application.

TiddlyWiki5 is currently at version 5.0.0.a3 and is under active development, which is to say that it is useful but incomplete. You can try out the online prototype at http://alpha.tiddlywiki.com/, try out the command line incarnation, get involved in the development on GitHub or join the discussions on the TiddlyWikiDev Google Group.

Overview

The heart of TiddlyWiki can be seen as an extensible representation transformation engine. Given the text of a tiddler and its associated ContentType, the engine can produce a rendering of the tiddler in a new ContentType. Furthermore, it can efficiently selectively update the rendering to track any changes in the tiddler or its dependents.

The most important transformations are from text/x-tiddlywiki wikitext into text/html or text/plain but the engine is used throughout the system for other transformations, such as converting images for display in HTML, sanitising fragments of JavaScript, and processing CSS.

The key feature of wikitext is the ability to include one tiddler within another (usually referred to as transclusion). For example, one could have a tiddler called Disclaimer that contains the boilerplate of a legal disclaimer, and then include it within lots of different tiddlers with the macro call <<tiddler Disclaimer>>. This simple feature brings great power in terms of encapsulating and reusing content, and evolving a clean, usable implementation architecture to support it efficiently is a key objective of the TiddlyWiki5 design.

It turns out that the transclusion capability combined with the selective refreshing mechanism provides a good foundation for building TiddlyWiki's user interface itself. Consider, for example, the StoryMacro in its simplest form:

<<story story:MyStoryTiddler>>

The story macro looks for a list of tiddler titles in the tiddler MyStoryTiddler, and displays them in sequence. The subtle part is that subsequently, if MyStoryTiddler changes, the <<story>> macro is selectively re-rendered. So, to navigate to a new tiddler, code merely needs to add the name of the tiddler and a line break to the top of MyStoryTiddler:

var storyTiddler = store.getTiddler("MyStoryTiddler");
store.addTiddler(new Tiddler(storyTiddler,{text: navigateTo + "\n" + storyTiddler.text}));

The mechanisms that allow all of this to work are fairly intricate. The sections below progressively build the key architectural concepts of TiddlyWiki5 in a way that should provide a good basis for exploring the code directly.

Introduction

TiddlyWiki5 is based on a 500 line boot kernel that runs on node.js or in the browser, and everything else is plugins.

The kernel boots just enough of the TiddlyWiki environment to allow it to load tiddlers as plugins and execute them (a barebones tiddler class, a barebones wiki store class, some utilities etc.). Plugin modules are written like node.js modules; you can use require() to invoke sub components and to control load order.

There are several different types of plugins: parsers, serializers, deserializers, macros etc. It goes much further than you might expect. For example, individual tiddler fields are plugins, too: there's a plugin that knows how to handle the tags field, and another that knows how to handle the special behaviour of the modified and created fields.

Some plugins have further sub-plugins: the wikitext parser, for instance, accepts rules as individual plugins.

Plugins and Modules

In TiddlyWiki5, a plugin is a bundle of related tiddlers that are distributed together as a single unit. Plugins can include tiddlers which are JavaScript modules.

The file core/boot.js is a barebones TiddlyWiki kernel that is just sufficient to load the core plugin modules and trigger a startup plugin module to load up the rest of the application.

The kernel includes:

• Eight short shared utility functions
• Three methods implementing the plugin module mechanism
• The $tw.Tiddler class (and three field definition plugins)
• The $tw.Wiki class (and three tiddler deserialization methods)
• Code for the browser to load tiddlers from the HTML DOM
• Code for the server to load tiddlers from the file system

Each module is an ordinary node.js-style module, using the require() function to access other modules and the exports global to return JavaScript values. The boot kernel smooths over the differences between node.js and the browser, allowing the same plugin modules to execute in both environments.

In the browser, core/boot.js is packed into a template HTML file that contains the following elements in order:

• Ordinary and shadow tiddlers, packed as HTML <DIV> elements
• core/bootprefix.js, containing a few lines to set up the plugin environment
• Plugin JavaScript modules, packed as HTML <SCRIPT> blocks
• core/boot.js, containing the boot kernel

On the server, core/boot.js is executed directly. It uses the node.js local file API to load plugins directly from the file system in the core/modules directory. The code loading is performed synchronously for brevity (and because the system is in any case inherently blocked until plugins are loaded).

The boot kernel sets up the $tw global variable that is used to store all the state data of the system.

Core

The 'core' is the boot kernel plus the set of plugin modules that it loads. It contains plugins of the following types:

• tiddlerfield - defines the characteristics of tiddler fields of a particular name
• tiddlerdeserializer - methods to extract tiddlers from text representations or the DOM
• startup - functions to be called by the kernel after booting
• global - members of the $tw global
• config - values to be merged over the $tw.config global
• utils - general purpose utility functions residing in $tw.utils
• tiddlermethod - additional methods for the $tw.Tiddler class
• wikimethod - additional methods for the $tw.Wiki class
• treeutils - static utility methods for parser tree nodes
• treenode - classes of parser tree nodes
• macro - macro definitions
• editor - interactive editors for different types of content
• parser - parsers for different types of content
• wikitextrule - individual rules for the wikitext parser
• command - individual commands for the $tw.Commander class

TiddlyWiki5 makes extensive use of JavaScript inheritance:

• Tree nodes defined in $:/core/treenodes/ all inherit from $:/core/treenodes/node.js
• Macros defined in $:/core/macros/ all inherit from $:/core/treenodes/macro.js

tiddlywiki.plugin files