README.md

javascript-astar

An implementation of the A* Search Algorithm in JavaScript

See a demo at http://www.briangrinstead.com/files/astar/

Sample Usage

If you want just the A* search code (not the demo visualization), use code like this http://gist.github.com/581352

<script type='text/javascript' src='astar.js'></script>
<script type='text/javascript'>
	var graph = new Graph([
		[1,1,1,1],
		[0,1,1,0],
		[0,0,1,1]
	]);
	var start = graph.grid[0][0];
	var end = graph.grid[1][2];
	var result = astar.search(graph, start, end);
	// result is an array containing the shortest path
	var graphDiagonal = new Graph([
		[1,1,1,1],
		[0,1,1,0],
		[0,0,1,1]
	], { diagonal: true });
	
	var start = graphDiagonal.grid[0][0];
	var end = graphDiagonal.grid[1][2];
	var resultWithDiagonals = astar.search(graphDiagonal, start, end, { heuristic: astar.heuristics.diagonal });
	// Weight can easily be added by increasing the values within the graph, and where 0 is infinite (a wall)
	var graphWithWeight = new Graph([
		[1,1,2,30],
		[0,4,1.3,0],
		[0,0,5,1]
	]);
	var startWithWeight = graphWithWeight.grid[0][0];
	var endWithWeight = graphWithWeight.grid[1][2];
	var resultWithWeight = astar.search(graphWithWeight, startWithWeight, endWithWeight);
	// resultWithWeight is an array containing the shortest path taking into account the weight of a node
</script>

A few notes about weight values:

1. A weight of 0 denotes a wall.
2. A weight cannot be negative.
3. A weight cannot be between 0 and 1 (exclusive).
4. A weight can contain decimal values (greater than 1).

Original (slower) implementation

The original version of the algorithm used a list, and was a bit clearer but much slower. It was based off the original blog post. The code is available at: https://github.com/bgrins/javascript-astar/tree/0.0.1/original-implementation.

The newest version of the algorithm using a Binary Heap. It is quite faster than the original. http://www.briangrinstead.com/blog/astar-search-algorithm-in-javascript-updated Binary Heap taken from http://eloquentjavascript.net/appendix2.html (license: http://creativecommons.org/licenses/by/3.0/)

Running the test suite

If you don't have grunt installed, follow the grunt getting started guide first.

Pull down the project, then run:

	npm install
	grunt