 function bark() {
  console.log('woof woof')
}
bark() // 'woof woof'


function Dog(age, weight) {
  this.species = 'Canis Familiaris'
  this.age = age
  this.weight = weight
  this.bark = bark //bark() function from above
}
// Spot and Bingo are 'instance-objects' of Dog
var Spot = new Dog(8, 65)
var Bingo = new Dog(10, 70)
console.log(Spot.species)// 'Canis Familiaris'
console.log(Spot);
//Dog {
//  species: 'Canis Familiaris',
//  age: 8,
//  weight: 65,
//  bark: [Function: bark]
//}

// bark is a 'method' of Dog
Bingo.bark()// 'woof woof'
console.log(Object.getPrototypeOf(Bingo) === Bingo.prototype); // false
console.log(Object.getPrototypeOf(Bingo) === Dog.prototype); // true
console.log(Bingo.__proto__ === Dog.prototype); //true
console.log(Dog.prototype);//Dog{}
console.log(Bingo.prototype);//undefined
console.log(Bingo.__proto__);//Dog{}

Dog.prototype.jump = function() {
    console.log('hop hop')
}
Spot.jump() //hop hop
Bingo.jump() // =>hop hop

console.log(Spot);
//Dog {
//  species: 'Canis Familiaris',
//  age: 8,
//  weight: 65,
//  bark: [Function: bark]
//}

console.log("***Dog***");

var insect = {legs: 6}
// insect.__proto__ === Object.prototype
// insect.hasOwnProperty === Object.prototype.hasOwnProperty
console.log(Object.getPrototypeOf(insect) === Object.prototype); //true
console.log(Object.getPrototypeOf(insect));//{}
console.log(Object.prototype); //{}
console.log(insect.__proto__); //{}
console.log(insect.prototype); //undefined
console.log(insect.hasOwnProperty('legs')) // => true

var Max = new Dog()
console.log(Max.__proto__ === Dog.prototype); //true
console.log(Max.__proto__); //Dog { jump: [Function] }
console.log(Max.prototype); //undefined
console.log(Dog.prototype.__proto__ === Object.prototype);//true
console.log(Dog.prototype.__proto__);//{}
console.log(Dog.prototype);//Dog { jump: [Function] }
console.log(Dog.prototype.hasOwnProperty('jump'));//true
console.log(Dog.prototype.hasOwnProperty('bark'));//false
console.log(Dog.__proto__ === Object.prototype);//false
console.log(Dog.__proto__);//[Function]
console.log(Max.hasOwnProperty('weight')); // => true

function Foo() {
    this.something = 'blah'
}
console.log(Foo.prototype.__proto__ === Object.prototype); //true
console.log(Foo.prototype.__proto__); //{}
console.log(Foo.prototype); //Foo {}
console.log(Foo.__proto__); //[Function]
console.log(Foo.hasOwnProperty('name')); // => true
console.log(Foo.name); //Foo
console.log(Foo.hasOwnProperty('something')); // false =>set on instance-object not on the function
console.log(Foo.something); //undefined
console.log(Foo.prototype.someting); //undefined

console.log("---------------");
var Max = new Dog();
console.log(Max.prototype); //undefined
console.log(Max.__proto__ === Dog.prototype); //true 
console.log(Max.__proto__); //Dog { jump: [Function] }
console.log(Dog.prototype); //Dog { jump: [Function] }
console.log(Dog.__proto__ === Function.prototype); //true     
console.log(Dog.__proto__); //[Function]
console.log(Function.prototype); //[Function]
console.log(Function.__proto__ === Function.prototype); //true  
console.log(Function.__proto__); //[Function]
console.log(Function.prototype); //[Function]

console.log("^^^^^^^^^^^^^");
var crab = {legs: 6};
console.log(crab.prototype); //undefined
console.log(crab.__proto__ === Object.prototype); //true
console.log(crab.__proto__); //{}
console.log(Object.prototype); //{}
console.log(Object.__proto__ === Function.prototype); //true  => Object() is a function object
console.log(Object.__proto__); //[Function]  
console.log(Function.prototype); //[Function]
console.log(Function.__proto__ === Function.prototype); //true  
console.log(Function.__proto__); //[Function]
console.log(Function.prototype); //[Function]
console.log(Function.prototype.__proto__ === Object.prototype); //true =>prototype is just an object
console.log(Object.prototype.__proto__);//null

console.log(Dog.prototype);//Dog { jump: [Function] }

console.log("############");
function Labrador(furColor, age, weight) {
    this.furColor = furColor
    this.breed = 'labrador'
    Dog.call(this, age, weight)
}
Labrador.prototype = Object.create(Dog.prototype)
console.log(Labrador.prototype);//Dog{}
var Fido = new Labrador('white', 4, 41)
console.log(Fido.__proto__); //Dog{}
Fido.bark(); //woof woof
Fido.jump(); //hop hop
console.log(Fido.furColor);//white
console.log(Fido.breed);//labrador
console.log(Fido.age);//4
console.log(Fido.constructor);

console.log(String.prototype.__proto__ === Object.prototype);//true
console.log(String.hasOwnProperty('length'));  //true




var myCar = new Object();
myCar.make = 'Ford';
myCar.model = 'Mustang';
myCar.year = 1969;

console.log(JSON.stringify(myCar)); //{"make":"Ford","model":"Mustang","year":1969}
console.log(myCar); //{ make: 'Ford', model: 'Mustang', year: 1969 }
console.log("***new Object()***");
console.log(myCar.prorotype); //undefined
console.log(myCar.__proto__); //{}
console.log("***new Object()***");



user = {
    x:5,
    sayHi: function() {
      console.log("Hello, this user object");
    },
    y:20
  };
console.log(JSON.stringify(user)); //{"x":5,"y":20}
console.log(user); //{ x: 5, sayHi: [Function: sayHi], y: 20 }
  
console.log("***object lateral***");
console.log(user.prorotype); //undefined
console.log(user.__proto__); //{}
console.log("***object lateral***");


console.log("***object.create()***");
var userTom = Object.create(user);
console.log(userTom.y); // 20
userTom.sayHi(); //Hello, this is user object
console.log(user.prorotype); //undefined
console.log(userTom.__proto__); //{ x: 5, sayHi: [Function: sayHi], y: 20 }
console.log(Object.getPrototypeOf(userTom) === user.prototype); //false
console.log(Object.getPrototypeOf(userTom));//{ x: 5, sayHi: [Function: sayHi], y: 20 }
//console.log(userTom instanceof user); //TypeError: Right-hand side of 'instanceof' is not callable
console.log(userTom);//{}
console.log("***object.create()***");


console.log("****new function()****")
function greeting(name) {
    this.names = name;
    this.isAdmin = false;
    console.log("hello, this is greeting function")
};
  
greeting(); //hello, this is greeting function
console.log(greeting.names); //undefined
console.log(greeting.name); //greeting
console.log(greeting);//[Function: greeting]

var g_obj = new greeting("John"); //hello this is greeting function
console.log(greeting.prototype); //greeting {}
console.log(g_obj.__proto__); //greeting {}
console.log(Object.getPrototypeOf(g_obj) === g_obj.prototype); //false
console.log(Object.getPrototypeOf(g_obj) === greeting.prototype); //true
  console.log(g_obj.__proto__ === greeting.prototype); //true
console.log(g_obj instanceof greeting); //true
console.log(g_obj); //greeting { names: 'John', isAdmin: false }
console.log(g_obj.prototype); //undefined
console.log("****new function()****")


function MyConstructor(name) {
  this.names = name;
  this.isAdmin = false;
  MyConstructor.fun1 = function(){};
  console.log("hello, this is greeting function too");
  this.fun3 = function(){console.log("hello, this is fun1")};
};
  //console.log(MyConstructor.fun1()); //TypeError: MyConstructor.fun1 is not a function
  console.log(MyConstructor.fun1); //undefined
  var myObj = new MyConstructor("John");
  myObj.fun1(); //undefined
  console.log(Object.getPrototypeOf(myObj) === myObj.prototype); // false
  console.log(Object.getPrototypeOf(myObj) === MyConstructor.prototype); // true
  console.log(myObj.__proto__ === MyConstructor.prototype); // true

  function MyConstructor(){
  };
  
  console.log(MyConstructor.prototype)  // MyConstructor {}

  MyConstructor.prototype.func2 = function(){
  };
  
  console.log(MyConstructor);  // [Function: MyConstructor]
  console.log(MyConstructor.prototype);  // MyConstructor { func2: [Function] }
  //MyConstructor.func2();  // TypeError: MyConstructor.func2 is not a function
console.log("****"); 



  function Person() {    
    this.name = "irshad"    
};    
var eve = new Person("Eve");    
console.log(Person); 
console.log(Person.prototype);    
console.log("*******"); 
console.log(eve.__proto__); //it will print the same as above    
console.log("*********"); 
eve.address = "ald";    
console.log(eve.__proto__ == Person.prototype); //true  

  var car = {
      model: 'bmw',
      color: 'red',
      price: 2000
  }
  console.log(JSON.stringify(car));
  car.type = 'manual'; // dynamic property  
  
  console.log(JSON.stringify(car));
  function Car(model, color) {
      this.model = model;
      this.color = color;
  }
  var c1 = new Car('BMW', 'red');
  console.log(c1);
  console.log(typeof(c1));
  
  // Function declaration.
  function showFavoriteIceCream() {
    const favIceCream = 'chocolate';
    console.log(`My favorite ice cream is ${favIceCream}`);
  }
  showFavoriteIceCream();
  
  // Let's assign a property.
  showFavoriteIceCream.flavours = ['chocolate', 'vanilla', 'strawberry'];
  
  // Let's log the showFavoriteIceCream function.
  console.log(showFavoriteIceCream);
  
  
  var obj = {prop1: 'prop1Value', prop2: 'prop2Value', child: {childProp1: 'childProp1Value'}}
  console.log(obj)
  
  console.log(JSON.stringify({ x: 5, y: 6 }));
  // expected output: "{"x":5,"y":6}"
  
  console.log(JSON.stringify([new Number(3), new String('false'), new Boolean(false)]));
  // expected output: "[3,"false",false]"
  
  console.log(JSON.stringify({ x: [10, undefined, function(){}, Symbol('')] }));
  // expected output: "{"x":[10,null,null,null]}"
  
  console.log(JSON.stringify(new Date(2006, 0, 2, 15, 4, 5)));
  // expected output: ""2006-01-02T15:04:05.000Z""

created 3 years ago

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

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

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");