A* Algorithm in JavaScript

astar.js

// A* pathfinding algorithm
function astar(start, end) {
    const openSet = [];
    const closedSet = [];
    openSet.push(start);

    while (openSet.length > 0) {
        let currentNode = openSet[0];
        // Find the node with the lowest total cost in the open set
        for (let i = 1; i < openSet.length; i++) {
            if (openSet[i].f < currentNode.f || (openSet[i].f === currentNode.f && openSet[i].h < currentNode.h)) {
                currentNode = openSet[i];
            }
        }

        openSet.splice(openSet.indexOf(currentNode), 1);
        closedSet.push(currentNode);

        if (currentNode.row === end.row && currentNode.col === end.col) {
            // Reconstruct the path if the goal is reached
            let path = [];
            let temp = currentNode;
            while (temp) {
                path.push(temp);
                temp = temp.parent;
            }
            return path.reverse();
        }

        const neighbors = [];
        const directions = [[0, 1], [1, 0], [0, -1], [-1, 0]];

        for (let dir of directions) {
            const neighborRow = currentNode.row + dir[0];
            const neighborCol = currentNode.col + dir[1];

            if (isValidCell(neighborRow, neighborCol)) {
                const neighbor = {
                    row: neighborRow,
                    col: neighborCol,
                    g: currentNode.g + 1,
                    h: heuristic({ row: neighborRow, col: neighborCol }, end),
                    f: 0,
                    parent: currentNode,
                };

                neighbor.f = neighbor.g + neighbor.h;

                if (closedSet.some((node) => node.row === neighbor.row && node.col === neighbor.col)) {
                    continue;
                }

                const openSetNode = openSet.find((node) => node.row === neighbor.row && node.col === neighbor.col);
                if (!openSetNode || neighbor.g < openSetNode.g) {
                    openSet.push(neighbor);
                }
            }
        }
    }

    // No path found
    return null;
}