Binary Search Tree in js

bst.js

class NodeTree{
	constructor(data, leftNode, rightNode){
		this.data = data;
		this.leftNode = leftNode;
		this.rightNode = rightNode;
	}

	display(){
		return this.data
	}
}


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

	insert(data){
		let newNode =  new NodeTree(data, null, null), current  =  this.root, parent;

		if(this.root == null){
			this.root =  newNode;
			return;
		}

		while(current != null){
			parent =  current;

			if(data < current.data){
				current = current.leftNode;
				if(current == null){
					parent.leftNode =   newNode;
					return;
				}
			}

			else{
				current =  current.rightNode
				if(current == null){
					parent.rightNode=  newNode;
					return;
				}
			}
		}
	}


	find(data){
		let current =  this.root;
		while(data != current.data){
			if(data < current.data) { current = current.leftNode; }
			else{ current =  current.rightNode; }
			if(current == null){return}
		}
		return current
	}
	findParent(data){
		let current =  this.root, parent;
		while(data != current.data){
			parent  = current;
			if(data < current.data) { current = current.leftNode; }
			else{ current =  current.rightNode; }
			if(current == null){return}
		}
		return parent
	}

	getMin(node){
		let current = node || this.root,parent  = current;
		while(current != null){
			parent =  current;
			current =  current.leftNode
		}
		return parent.data;
	}

	getMax(node){
		let current =  node || this.root,parent  = current;
		while(current != null){
			parent =  current;
			current =  current.rightNode
		}
		return parent.data;
	}

	inOrder(node){
		if(node != null){
			this.inOrder(node.leftNode);
			node.display();
			this.inOrder(node.rightNode);
		}
	}
	preOrder(node){
		if(node != null){
			node.display();
			this.preOrder(node.leftNode);
			this.preOrder(node.rightNode);
		}	
	}
	postOrder(node){
		if(node != null){
			this.postOrder(node.leftNode);
			this.postOrder(node.rightNode);
			node.display();
		}	
	}

	delete(data){
		let ele = this.find(data), parent = this.findParent(data);

		//Node is a leaf
		if(ele.leftNode == null && ele.rightNode == null){
			if(ele == this.root) this.root  = null; return
			if(parent.leftNode == ele) parent.leftNode = null
			else parent.rightNode = null
		}
			/*Node has one child*/
		else if(ele.leftNode == null) parent.rightNode =  ele.rightNode;
		else if(ele.rightNode == null) parent.leftNode =  ele.leftNode;

			/*Node has two children*/ 
		else{
			let smallest = this.getMin(ele);
			ele.data = smallest;
			delete(smallest);
		}

	}
}