breadthFirstSearch on a Tree . Check out https://levelup.gitconnected.com/finding-the-shortest-path-in-javascript-pt-1-breadth-first-search-67ae4653dbec

breadthFirstSearch.js

/*
     10
    /  \
   4    17
  / \   / \
 1   9 12  18 
 
let tree = {
	"10": {
		value: "10",
		left: "4",
		right: "17",
	},
	"4": {
		value: "4",
		left: "1",
		right: "9",
	},
	"17": {
		value: "17",
		left: "12",
		right: "18",
	},
	"1": {
		value: "1",
		left: null,
		right: null,
	},
	"9": {
		value: "9",
		left: null,
		right: null,
	},
	"12": {
		value: "12",
		left: null,
		right: null,
	},
	"18": {
		value: "18",
		left: null,
		right: null,
	},
};
*/
let BreadthFirstSearch = (tree, rootNode, searchValue) => {
  //make queue
  let queue = [];
  //populate it with node that will be the root of your search
  queue.push(rootNode);

  //search the queue until it is empty
  while (queue.length > 0) {
    // assign the top of the queue to variable currentNode

    let currentNode = queue[0];

    // if currentNode is the node we're searching for, break & alert

    if (currentNode.value === searchValue) {
      console.log('Found it');
      return;
    }
    // if currentNode has a left child node, add it to the queue.

    if (currentNode.left !== null) {
      queue.push(tree[currentNode.left]);
    }

    // if currentNode has a right child node, add it to the queue.
    if (currentNode.right !== null) {
      queue.push(tree[currentNode.right]);
    }

    // remove the currentNode from the queue.
    queue.shift();
  }
  console.log('Sorry, no such node found :(');
};