treeSearching.js

class Node {
  constructor(value) {
    this.value = value
  }
}

class Tree {
  add(node) {
    if (!this.root) {
      this.root = node
      return
    }

    let current = this.root

    while(current) {
      if (node.value > current.value) {
        if (current.right) {
          current = current.right
        } else {
          current.right = node
          node.parent = current.right
          return
        }
      } else {
        if (current.left) {
          current = current.left
        } else {
          current.left = node
          node.parent = current.left
          return
        }
      }
    }
  }

  addAllValues(arr) {
    for(let num of arr) {
      this.add(new Node(num))
    }
  }

  dfs(val, root = this.root) {
    if (root.value === val) return root

    if (root.left) {
      let foundLeft = this.dfs(val, root.left)
      if (foundLeft) return foundLeft
    }

    if (root.right) {
      let foundRight = this.dfs(val, root.right)
      if (foundRight) return foundRight
    }
  }

  bfs(val) {
    if (val === this.root.value) return this.root
    return this._bfs(val, this.root)
  }

  // Separate function is necessary to avoid checking 
  // the parent's value twice
  _bfs(val, root) {
    if (root.left  && root.left.value  === val) return root.left
    if (root.right && root.right.value === val) return root.right

    if (root.left) {
      let foundLeft = this._bfs(val, root.left)
      if (foundLeft) return foundLeft
    }

    if (root.right) {
      let foundRight = this._bfs(val, root.right)
      if (foundRight) return foundRight
    }
  }
}

let tree = new Tree()
tree.addAllValues([5, 3, 7, 1, 2, 9, 8, 11])

console.log(tree.bfs(8))