# JavaScripting

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## Javascript Astar

A* Search / Pathfinding Algorithm in Javascript
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# javascript-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;
var end = graph.grid;
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;
var end = graphDiagonal.grid;
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;
var endWithWeight = graphWithWeight.grid;
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
``````