Basic binary Tree in JavaScript

Question

I wrote a basic binary tree in JS. Can anyone give me some feedback about my code?

I just want to know if this is the right approach, and how I can improve the tree. I am new to JavaScript and data structures.

function bst() {
 this.root = null;
}
bst.prototype.insert = function( obj ){
 if ( this.root == null ){
 this.root = new node(obj);
 }
 else if (this.root.value > obj){
 if (this.root.left != null ){
 this.root.left.insert( obj );
 }
 else {
 this.root.left = new node(obj);
 }
 } 
 else if (this.root.value < obj){
 if (this.root.right != null ){
 this.root.right.insert( obj );
 }
 else {
 this.root.right = new node(obj);
 }
 }
}
 function node( obj ){
 this.left = null;
 this.right = null;
 this.value = obj;
 }
node.prototype.insert = function( obj ){
if (this.value > obj){
 if (this.left != null){
 this.left.insert( obj )
 }
 else{
 this.left = new node(obj);
 }
}
else if (this.value < obj){
 if (this.right != null){
 this.right.insert( obj )
 }
 else{
 this.right = new node(obj);
 }
}
//elase duplicated key value
else{
 console.log("duplicated bst key")
}
}
var bst = new bst();
bst.insert(25);
bst.insert(75);
bst.insert(12);
bst.insert(37);
bst.insert(87);
bst.insert(63);
console.log(bst.root.value);
console.log(bst.root.left.value);
console.log(bst.root.right.value);
console.log(bst.root.right.left.value);
console.log(bst.root.right.right.value);
console.log(bst.root.right.left.right.value);

Answer 1

I can see two obvious points:

• Constructor names are usually capitalized, to indicate that they should be invoked with new
• You've got some code duplication between bst::insert and node::insert. This even leads to the bug that you don't recognise/handle duplicate values in the root node.

So, I'd suggest:

function Bst() {
 this.root = null;
}
Bst.prototype.insert = function(obj) {
 if (this.root == null) {
 this.root = new Node(obj);
 } else {
 this.root.insert(obj);
 }
};

I am new to data structures.

Binary trees are a wide field :-) First, I'm missing some other basic operations like searching, traversing, and deleting. If you have mastered these, you can go on with optimizing your tree, e.g. making it a balanced one.