# Breadth-First Traversal of a Tree Data Structure

By Hemanta Sundaray on 2021-11-07

### Direction

Implement a method named traverseBF on the Tree class. The traverseBF method should accept a function that gets called with each node in the tree.

With breadth-first traversal, we start iterating at each level of the tree:

### The algorithm

We will implement the traverseBF method using the following algorithm:

Consider the following tree data structure:

First, we will create an empty array and push the root node into it.

Then we will iterate through the array based on the condition that the array has some elements in it. Next, we will remove the first element from the array, then retrieve all of its children and push them into the array.

Thereafter, we will pass the element (removed from the array in the previos step) to the function received as an argument to the traverseBF method. Then, we will remove the first element from the array and the process continues.

### Implementation using JavaScript

``````class Node {
constructor(data) {
this.data = data
this.children = []
}

this.children.push(new Node(data))
}

remove(data) {
this.children = this.children.filter(node => node.data !== data)
}
}

class Tree {
constructor() {
this.root = null
}

traverseBF(fn) {
// create an empty array and push the root node into it
const arr = [this.root]
// while there are some elements in the array
while (arr.length > 0) {
// remove the first element from the array using the shift() method
const node = arr.shift()
// then, push the children of the node (removed from the array in the previous step) into the array
arr.push(...node.children)
// pass the removed node as an argument to the function passed as an argument to the traverseBF method.
fn(node)
}
}
}``````