How to determine if there exists a route between two nodes in JavaScript

// BFS
function search(graph, start, end) {
    if (start === end) return true;
    
    // functions like a queue
    const queue = [];
    
    for (const node of graph.getNodes()) {
        node.state = 'unvisited';
    }
    
    start.state = 'visiting';
    
    queue.push(start);
    
    let node;
    
    while (queue.length) {
        node = queue.shift(); // dequeue
        if (node) {
            for (const neighbor of graph.getAdjacentNeighbors(node)) {
                if (neighbor.state === 'unvisited') {
                    if (neighbor === end) {
                        return true;
                    } else {
                        neighbor.state = 'visiting';
                        queue.push(neighbor); // enqueue
                    }
                }
            }
            node.state = 'visited';
        }
    }
    return false;
}
// Adjacency list representation of a graph
function Graph(iterable) {
  this.list = new Map(iterable); // [[key, value], [key, value]]
}
Graph.prototype.addVertex = function(vertex) {
  !this.list.get(vertex) && this.list.set(vertex, []); // prevents overwriting a vertex
}
Graph.prototype.addEdge = function(from, to) {
  this.list.get(from).push(to) // does not account for edge case where we try to add edge again
  this.list.get(to).push(from);
}
Graph.prototype.getNodes = function() {
  return Array.from(this.list.keys());
};
Graph.prototype.getAdjacentNeighbors = function(target) {
  return this.list.get(target) || [];
}