a star in javascript

index.tsx
function aStar(start, target, graph) {
  const queue = new PriorityQueue();
  const visited = new Set();
  const costs = {};
  const previous = {};

  // Initialize starting node
  queue.enqueue(start, 0);
  visited.add(start);
  costs[start] = 0;

  while (!queue.isEmpty()) {
    const current = queue.dequeue();

    if (current === target) {
      return reconstructPath(start, target, previous);
    }

    graph[current].forEach(neighbor => {
      const cost = costs[current] + neighbor.cost;
      if (!visited.has(neighbor.node) || cost < costs[neighbor.node]) {
        visited.add(neighbor.node);
        costs[neighbor.node] = cost;
        const priority = cost + heuristic(neighbor.node, target);
        queue.enqueue(neighbor.node, priority);
        previous[neighbor.node] = current;
      }
    });
  }

  // Target node is not reachable from start node
  return null;
}

function reconstructPath(start, target, previous) {
  const path = [];
  let current = target;

  while (current !== start) {
    path.push(current);
    current = previous[current];
  }

  path.push(start);
  return path.reverse();
}

function heuristic(node, target) {
  // Manhatten distance heuristic
  const [x1, y1] = node.split(',');
  const [x2, y2] = target.split(',');
  return Math.abs(x1 - x2) + Math.abs(y1 - y2);
}

class PriorityQueue {
  constructor() {
    this.items = [];
  }

  enqueue(item, priority) {
    this.items.push({ item, priority });
    this.items.sort((a, b) => a.priority - b.priority);
  }

  dequeue() {
    return this.items.shift().item;
  }

  isEmpty() {
    return this.items.length === 0;
  }
}
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