class Graph {
  
    	constructor(noOfVertices)
    	{
    		this.noOfVertices = noOfVertices
    		this.AdjList = new Map()
    	}

      // add vertex to the graph
      addVertex(v)
      {
      	this.AdjList.set(v, [])
      }
      // add edge to the graph
      addEdge(v, w)
      {
      	//add an edge from v to w also
      	this.AdjList.get(v).push(w)
      
      	// add an edge from w to v also
      	this.AdjList.get(w).push(v)
      }
// Prints the vertex and adjacency list
    printGraph()
    {
    	// get all the vertices
    	var get_keys = this.AdjList.keys()
    
    	// iterate over the vertices
      	for (var i of get_keys)
        {
      		// great the corresponding adjacency list for the vertex
      		var get_values = this.AdjList.get(i)
      		var conc = ""
      
      		// iterate over the adjacency list concatenate the values into a string
      		for (var j of get_values)
      			conc += j + " ";
      
      		// print the vertex and its adjacency list
      		console.log(i + " -> " + conc);
      	}
    }
    
    bfs(startingNode)
    {
        // create a visited object
        var visited = {};
      
        // Create an object for queue
        var q = new Queue();
      
        // add the starting node to the queue
        visited[startingNode] = true;
        q.enqueue(startingNode);
      
        // loop until queue is element
        while (!q.isEmpty()) 
        {
            // get the element from the queue
            var getQueueElement = q.dequeue();
      
            // passing the current vertex to callback funtion
            console.log(getQueueElement);
      
            // get the adjacent list for current vertex
            var get_List = this.AdjList.get(getQueueElement);
      
            // loop through the list and add the element to the
            // queue if it is not processed yet
            for (var i in get_List) {
                var neighbour = get_List[i];
      
                if (!visited[neighbour]) {
                    visited[neighbour] = true;
                    q.enqueue(neighbour);
                }
            }
        }
    }
    dfs(startingNode)
    {
      
        var visited = {};
        this.DFS_traversal(startingNode, visited);
    }
      
    // Recursive function which process and explore
    // all the adjacent vertex of the vertex with which it is called
    DFS_traversal(vert, visited)
    {
        visited[vert] = true;
        console.log(vert);
      
        var get_neighbours = this.AdjList.get(vert);
      
        for (var i in get_neighbours) {
            var get_elem = get_neighbours[i];
            if (!visited[get_elem])
                this.DFS_traversal(get_elem, visited);
        }
    }

}
class Queue
{
    // Array is used to implement a Queue
    constructor()
    {
        this.items = [];
    }
                  
    enqueue(element)
    {    
        // adding element to the queue
        this.items.push(element);
    }
    dequeue()
    {
        
        if(this.isEmpty())
            return "Underflow";
        return this.items.shift();
    }
   
    isEmpty()
    {
        // return true if the queue is empty.
        return this.items.length == 0;
    }
   
}

var g = new Graph(6);
var vertices = ['A','B','C','D','E','F'];
for (var i = 0; i < vertices.length; i++)
{
    g.addVertex(vertices[i]);
}
  
// adding edges
g.addEdge('A', 'B');
g.addEdge('A', 'D');
g.addEdge('A', 'E');
g.addEdge('B', 'C');
g.addEdge('D', 'E');
g.addEdge('E', 'F');
g.addEdge('E', 'C');
g.addEdge('C', 'F');
g.printGraph();
console.log("BFS");
g.bfs('A');
console.log("DFS");
g.dfs('A');

Javascript Online Compiler

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.

About Javascript

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.

Key Features

  • Open-source
  • Just-in-time compiled language
  • Embedded along with HTML and makes web pages alive
  • Originally named as LiveScript.
  • Executable in both browser and server which has Javascript engines like V8(chrome), SpiderMonkey(Firefox) etc.

Syntax help

STDIN Example

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);
});

variable declaration

KeywordDescriptionScope
varVar is used to declare variables(old way of declaring variables)Function or global scope
letlet is also used to declare variables(new way)Global or block Scope
constconst is used to declare const values. Once the value is assigned, it can not be modifiedGlobal or block Scope

Backtick Strings

Interpolation

let greetings = `Hello ${name}`

Multi line Strings

const msg = `
hello
world!
`

Arrays

An array is a collection of items or values.

Syntax:

let arrayName = [value1, value2,..etc];
// or
let arrayName = new Array("value1","value2",..etc);

Example:

let mobiles = ["iPhone", "Samsung", "Pixel"];

// accessing an array
console.log(mobiles[0]);

// changing an array element
mobiles[3] = "Nokia";

Arrow functions

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.

Syntax:

() => expression

Example:

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);

De-structuring

Arrays

let [firstName, lastName] = ['Foo', 'Bar']

Objects

let {firstName, lastName} = {
  firstName: 'Foo',
  lastName: 'Bar'
}

rest(...) operator

 const {
    title,
    firstName,
    lastName,
    ...rest
  } = record;

Spread(...) operator

//Object spread
const post = {
  ...options,
  type: "new"
}
//array spread
const users = [
  ...adminUsers,
  ...normalUsers
]

Functions

function greetings({ name = 'Foo' } = {}) { //Defaulting name to Foo
  console.log(`Hello ${name}!`);
}
 
greet() // Hello Foo
greet({ name: 'Bar' }) // Hi Bar

Loops

1. If:

IF is used to execute a block of code based on a condition.

Syntax

if(condition){
    // code
}

2. If-Else:

Else part is used to execute the block of code when the condition fails.

Syntax

if(condition){
    // code
} else {
    // code
}

3. Switch:

Switch is used to replace nested If-Else statements.

Syntax

switch(condition){
    case 'value1' :
        //code
        [break;]
    case 'value2' :
        //code
        [break;]
    .......
    default :
        //code
        [break;]
}

4. For

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
//code  
}

5. While

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 
}

6. Do-While

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);

Classes

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.

Syntax:

class className {
  constructor() { ... } //Mandatory Class method
  method1() { ... }
  method2() { ... }
  ...
}

Example:

class Mobile {
  constructor(model) {
    this.name = model;
  }
}

mbl = new Mobile("iPhone");