//create a node class
class Node {
constructor(value) {
this.left = null;
this.right = null;
this.value = value;
}
}
//create a class for binary search tree
class BinarySearchTree {
constructor() {
this.root = null;
}
//create insert tree
insert(value) {
let newNode= new Node(value);
// to insert we want to check if root is empty or not
if(!this.root){
this.root = newNode;
}else{
let currentNode= this.root;
while(true){
if(value < currentNode.value){
if(!currentNode.left){
currentNode.left=newNode;
//console.log('current.left:',this);
return this
}
currentNode=currentNode.left
}else{
if(!currentNode.right){
currentNode.right=newNode;
//console.log('current.right:',this);
return this;
}
currentNode=currentNode.right;
}
}
}
}
//create lookup()
//create scenerio where there is no root
//create a situation which currentNode is always true. That currentNode should be changing
//node as we iterate. currentNode should should be larger,smaller,equal or not exist. If it
//doesnt exist then return false
lookup(value) {
if(!this.root){
console.log('No root');
}else{
let currentNode=this.root;
let parentNode;
while(currentNode){
if(value<currentNode.value){
currentNode=currentNode.left;
}else if(value>currentNode.value){
currentNode=currentNode.right;
}else if(value === currentNode.value){
console.log('equals at:',currentNode);
return currentNode;
}
}
console.log('false || no node found')
return false;
}
}
//create remove();
//we want to use look up() logic. Inside condition of ==. Inside that create a situation
//of currentNode having no children, 2 children or none.
remove(value) {
if(!this.root){
console.log('No root');
}else{
let currentNode=this.root;
let parentNode;
while(currentNode){
if(value<currentNode.value){
parentNode=currentNode;
currentNode=currentNode.left;
}else if(value>currentNode.value){
parentNode=currentNode;
currentNode=currentNode.right;
}else if(value === currentNode.value){
//No children
if(!currentNode.left && !currentNode.right){
console.log('no children')
if(parentNode.left==currentNode){
parentNode.left=null;
}else{
parentNode.right=null;
}
}
else if(currentNode.left && currentNode.right){
// Two children
//we need to keep track of the parent and right child in a variable.
//use iteration to check if left child is not null. if not null we make the child into the parent
// the new child from previous left child
// out of iteration or if child is null we make current.value be the child value
//Use a conditional if left child equals to current child then we make left child equal
//current child right else right child equal current child right.
console.log(' two children')
let successorParent=currentNode;
let successor=currentNode.right;
while(successor.left !== null){
successorParent=successor;
successor=successor.left;
}
currentNode.value=successor.value;
console.log('SUCCessorParent:',successorParent)
if(successorParent.left==successor){
console.log('***********1')
successorParent.left=successor.right;
console.log('SUCCESSOR RIGHT:',successorParent.left);
}else{
successorParent.right=successor.right;
}
}
else{
// One child
//create a ternary that makes childnot currentNode left. if true return currentNode left
//if false return currentNode right
// create else statement that if left child = currentNode return child left=childnode
//else right child equal childnode
//
console.log('one children')
let childNode= currentNode.left ? currentNode.left : currentNode.right;
if(parentNode.left==currentNode){
parentNode.left=childNode;
}else{
parentNode.right=childNode;
}
}
console.log('Remove answer:',this);
return;
//return currentNode;
}
}
console.log('false || no node found')
return false;
}
}
}
const tree = new BinarySearchTree();
tree.insert(9);
tree.insert(4);
tree.insert(1);
tree.insert(6);
tree.insert(20);
tree.insert(15);
tree.insert(170);
tree.remove(170);
// tree.insert(15);
// tree.insert(1);
// tree.lookup(57);
JSON.stringify(traverse(tree.root));
// console.log(tree.lookup(20));
// 9
// 4 20
//1 6 15 170
function traverse(node) {
const tree = { value: node.value };
tree.left = node.left === null ? null : traverse(node.left);
tree.right = node.right === null ? null : traverse(node.right);
console.log('tree:',tree);
return tree;
}
//root. If root==value
//savedRoot=this.root;
//if value == this.root, go right by making currentNode=currentNode.right. if currentnode.left
//then make currentNode=currentNode.left
//Make currentNode.right=savedRoot.right
//make savedRoot.right.left=null;
// if (value == this.root.value){
// console.log('1');
// let currentNode=this.root;
// console.log('**:',currentNode.right.left);
// if(currentNode.right.left){
// console.log('2');
// let target=currentNode.right.left;
// target.right=this.root.right;
// this.root.right.left=null;
// target.left=this.root.left;
// this.root=target;
// }
// }
// if(value<this.root.value){
// if(this.root.left.value==value){
// let target=this.root.left;
// if(target.right){
// target.right.left=target.left;
// target=target.right;
// this.root.left=target;
// target.right=null;
// }
// }
// }
// if(value>this.root.value){
// let target=this.root.right;
// if(target.value==value && target.left){
// target.left.right=target.right;
// target=target.left;
// this.root.right=target;
// }
// }
//left child. If value<root
//if this.root.left == value
//let target=this.root.left;
//if(target.right)
//target.right.left=target.left
//target=target.right
//this.root.left=target
//right child. If value>root
//let target = this.root.right
//if target==value && target.left
//target.left.right==target.right
//target=target.left
//this.root.right=target
//console.log('remove answer:',this);
Write, Run & Share Javascript code online using OneCompiler's JS online compiler for free. It's one of the robust, feature-rich online compilers for Javascript language. Getting started with the OneCompiler's Javascript editor is easy and fast. The editor shows sample boilerplate code when you choose language as Javascript and start coding.
Javascript(JS) is a object-oriented programming language which adhere to ECMA Script Standards. Javascript is required to design the behaviour of the web pages.
var readline = require('readline');
var rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
terminal: false
});
rl.on('line', function(line){
console.log("Hello, " + line);
});
| Keyword | Description | Scope |
|---|---|---|
| var | Var is used to declare variables(old way of declaring variables) | Function or global scope |
| let | let is also used to declare variables(new way) | Global or block Scope |
| const | const is used to declare const values. Once the value is assigned, it can not be modified | Global or block Scope |
let greetings = `Hello ${name}`
const msg = `
hello
world!
`
An array is a collection of items or values.
let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);
let mobiles = ["iPhone", "Samsung", "Pixel"];
// accessing an array
console.log(mobiles[0]);
// changing an array element
mobiles[3] = "Nokia";
Arrow Functions helps developers to write code in concise way, it’s introduced in ES6.
Arrow functions can be written in multiple ways. Below are couple of ways to use arrow function but it can be written in many other ways as well.
() => expression
const numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
const squaresOfEvenNumbers = numbers.filter(ele => ele % 2 == 0)
.map(ele => ele ** 2);
console.log(squaresOfEvenNumbers);
let [firstName, lastName] = ['Foo', 'Bar']
let {firstName, lastName} = {
firstName: 'Foo',
lastName: 'Bar'
}
const {
title,
firstName,
lastName,
...rest
} = record;
//Object spread
const post = {
...options,
type: "new"
}
//array spread
const users = [
...adminUsers,
...normalUsers
]
function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
console.log(`Hello ${name}!`);
}
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar
IF is used to execute a block of code based on a condition.
if(condition){
// code
}
Else part is used to execute the block of code when the condition fails.
if(condition){
// code
} else {
// code
}
Switch is used to replace nested If-Else statements.
switch(condition){
case 'value1' :
//code
[break;]
case 'value2' :
//code
[break;]
.......
default :
//code
[break;]
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
//code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while (condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
ES6 introduced classes along with OOPS concepts in JS. Class is similar to a function which you can think like kind of template which will get called when ever you initialize class.
class className {
constructor() { ... } //Mandatory Class method
method1() { ... }
method2() { ... }
...
}
class Mobile {
constructor(model) {
this.name = model;
}
}
mbl = new Mobile("iPhone");