Binary Search Tree Class Shell

bst-shell-es5.js

//ES5 version
function TreeNode(keyValue) {
    this.keyValue = keyValue;
    this.left = null;
    this.right = null;
    this.toString = function() {
        return this.keyValue;
    }
}

function BinarySearchTree() {
    var rootNode = null;
}

bst-shell-modern.js

//ES2015 & beyond version
class TreeNode {
    constructor(keyValue) {
        this.keyValue = keyValue;
        this.left = null;
        this.right = null;
    }
}

class BinarySearchTree {
  constructor() {
    let rootNode = null;
  }
  
  toString() {
    return this.keyValue;
  }
}