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