code: function AStar(isWalkable) {
    this.destX = 0;
    this.destY = 0;
    this.scaleX = 1;
    this.scaleY = 1;
    this.openNodes = {};
    this.closedNodes = {};
    this.openHeap = new BinaryHeap(function(a, b) {
      return a.f - b.f;
    });
    this.isWalkable = isWalkable;
  }
docs: Implements the [A* pathfinding algorithm]{@link http://en.wikipedia.org/wiki/A*_search_algorithm} on a 2-dimensional grid. You can use this to find a path between a source and destination coordinate while avoiding obstacles.
  @constructor
  @alias Splat.AStar
  @param {isWalkable} isWalkable A function to test if a coordinate is walkable by the entity you're performing the pathfinding for.