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CoffeeScript Mazes

There are a lot of different maze algorithms out there, each with different properties, strengths, weaknesses, and interesting points. The aim of this project is to develop a library of these algorithms in a format that allows the inner structure and behavior of them to be studied and observed visually, by animating them and allowing students to step through them.


You'll need CoffeeScript installed. Once you've got that, you can run:

cake build

This will convert the CoffeeScript sources in the "src" directory, to Javascript files in the "lib" directory.

At this point you should be able to open the demo in examples/maze.html. (A possibly-out-of-date version of the demo can be seen here, if you want to get an idea of what csMazes can do.)

If you want to do a piecemeal installation of your own, you'll need at least these files, included in this order:

  • mersenne.js
  • maze.js

Further, the "widget.js" includes a script for easily embedding maze animations on your page; you just need to add the CSS definitions. (See examples/maze.html for the CSS definitions.)

Once you've included those files, you can include any of the algorithm-specific files you want.

Also, these files may be safely combined and minified, if you want to reduce everything to a single file.


Using the included widget, embedding a maze is as simple as this:

<script type="text/javascript">
  Maze.createWidget("Prim", 10, 10)

This would embed a 10x10 grid that will animate Prim's algorithm. You can also pass an optional object (hash) with properties to customize how the algorithm runs, or how the grid is displayed. These properties are supported:

  • id : used to set the id of the created HTML elements. If not specified, the lower-cased algorithm name will be used.
  • class : the HTML class attribute to add to the outermost generated div. This is in addition to any other classes that the widget itself assigns (e.g. "maze").
  • input : data that should be passed to the maze object upon creation. This should be either a string, in which case it is passed directly to the maze constructor, or a function, in which case it is invoked first and the return value used as the value passed to the maze. The actual format of the string is dependent on the algorithm used.
  • interval : the delay (in milliseconds) between steps when the maze is in "run" mode. Defaults to 50ms.
  • wallwise : a boolean value indicating whether the maze is to be displayed as a passage carver (false) or a wall adder (true). The meaning of the wall queries is inverted when wallwise is true. Most mazes need to have wallwise set to false (the default), but the RecursiveDivision algorithm is a wall adder and needs to be rendered with wallwise set to true.
  • seed : an integer value to use as a seed for the random number generated. Using the same seed for different animation runs (where the algorithm and dimensions are otherwise the same) will always result in the same maze being generated.
  • rng : the random number generator object to use to generate numbers. You'll almost never need to use this; but it could be handy if you want to generate a series of mazes with the same original seed. If used, this should be an instance of MersenneTwister (defined in, or should at least conform to the same interface.
  • padded : if true, adds space around each cell. The default is false.
  • weave : if true, generates a "weave" maze (where passages move over and under other passages). This is not supported by all algorithms. For best results, use with padded set to true.
  • weaveMode : either, "onePhase" (the default), or "twoPhase". Only Kruskal's algorithm currently supports this setting.
  • weaveDensity : A number between 0 and 100 (default 80), with 100 meaning "maximum" density". Only used when weaveMode is set to "twoPhase".

Advanced Usage

If you're determined to do things the hard way, you can always instantiate the mazes yourself, setting up the callbacks and rendering things manually. To instantiate a maze:

var maze = new Maze(10, 10, Maze.Algorithms.Prim)

This would create a blank 10x10 grid that will generate a maze using Prim's algorithm. Mazes are generated either step-wise:

maze.step() // returns false when the maze is completed

Or they can be generated all at once:

maze.generate() // calls step() repeatedly until done

As with the widget helper, the maze constructor accepts an optional final parameter, an object, whose properties can be used to customize how the maze is built. The following properties are understood (and have the same meaning as their counterparts in the widget helper):

  • input : a string used as input to the algorithm, which can be used to customize its behavior. Not all algorithms use this parameter.
  • seed
  • rng
  • weave
  • weaveMode
  • weaveDensity

To indicate interest in the progress of the maze, you can use the onUpdate and onEvent methods to register callbacks that will be invoked. The onUpdate callback is triggered every time a cell is changed. The onEvent callback is triggered whenever an algorithm-dependent "event" occurs (e.g. the recursive backtracker hits a dead-end and has to backtrack). Both callbacks accept three parameters: the maze object that caused the callback, and the x and y coordinates that are relevant.

maze.onUpdate(function(m, x, y) {
  // update the display, etc.

maze.onEvent(function(m, x, y) {
  // pause the animation, etc.


csMazes is written by Jamis Buck ( and is made available in the public domain. Do with it what you will.

But please prefer good over evil.


Maze algorithms implemented in CoffeeScript, with an eye toward demonstrating how the algorithms work by animating them.







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