Insertion in a Binary in Level Order using JavaScript

Fig 1

In level order insertion node get inserted into the binary tree level by level. No node will be inserted into the next level until the last level is filled.

In Fig 1 we need to insert node 5. At levels 0 and 1, there are no vacant spaces. At level 2, node 2 doesn’t have any left children and node 3 does not have any children, but the first vacant space is the left child of node 2, so node 5 will be inserted as shown in fig 1.

We can initialise a tree as follows.

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

Tree consist of nodes, so we should have one node class.

class Node {
constructor(data) {
this.data = data;
this.left = null;
this.right = null;
}
}

Now, we need to create a method to insert nodes in tree.

If tree is not having any node then new node will be root.

insert(data){
if(this.root===null)
this.root= new Node(data)
}

Here this.root will refer to root of the tree because insert method is created inside tree class.