Implementation of breadth-first search in JavaScript.

breadth-first-search.js

// Implementation of breadth-first search in JavaScript.

function breadthFirstSearch(g, start, end) {
  const queue = [[start]];
  const visited = {};
  while (queue.length > 0) {
    const path = queue.shift();
    const node = path[path.length - 1];
    if (node === end) {
      console.log("number of steps:", path.length - 1);
      console.log("path:", path.join(" -> "));
      return g[node];
    }
    visited[node] = true;
    for (const neighbor of g[node]) {
      const newSteps = [...path, neighbor];
      if (!visited[neighbor]) {
        queue.push(newSteps);
      }
    }
  }
  console.log(`No path from ${start} to ${end}`);
}

const graph = {
  you: ["bob", "alice", "jake", "carol"],
  bob: ["larry", "tony", "sara"],
  alice: ["henry", "daryl", "tony"],
  jake: ["bob"],
  carol: ["daryl", "henry"],
  larry: ["you", "alice", "tony"],
  tony: ["henry", "you", "alice"],
  sara: ["alice", "carol", "mary"],
  mary: ["jake", "larry", "carol"],
  henry: ["mary", "carol", "alice", "larry"],
  daryl: ["tony"],
  tony: ["alice"],
  circleA: ["circleB"],
  circleB: ["circleC"],
  circleC: ["circleA"],
};

console.log(breadthFirstSearch(graph, "you", "mary"));