Javascript Questions Interview

q.js

//           1  '2'  Number('2')
function sum(a, b) {

	 return a + b;//+ operatorul concateneaza
	                //dubla semnificatie: prima semnificatie adunare in sens matematic, a doua semnificatie concateneaza doua string-uri  
}

//*,/,- transforma in Number

//coercion 
/*

A: NaN
B: TypeError
C: "12"//
D: 3

*/

console.log ( sum(1,'2') )


function bark() {

  console.log("Woolf");	
}

bark.animal = 'dog'
bark.culoare = 'abc'

/*
A: nothing, totul este ok (Correct answer)
B: Syntax Error
C: "woolf" este inregistrat
D: ReferenceError

Toate functiile in JS sunt obiecte 
O functie este un tip special de OBJECT
*/

//bark()


function Person(firstname, lastname) {

	 this.firstname = firstname
	 this.lastname = lastname
}

//creeaza un obiect
const member = new Person("John","Fatima")

Person.prototype.getFullName = function() {
	 return `${this.firstname} ${this.lastname}`
}

console.log(member.getFullName())

/*
A: TypeError
B: SyntaxError
C: John Fatima
D: undefined undefined

In JS prototype este un mecanism prin care obiectele pot mosteni proprietati si metode de la alte obiecte


function Person(name) {
	
	this.name = name;
} 

const ana = new Person("Ana")
const ion = new Person("Ion")

Person.prototype.sayHello = function() {
	
	  console.log(`Salut, sunt ${name}`)
}

ana.sayHello() //Salut, sunt Ana
io.sayHello() //Salut, sunt Ion
*/

/*
function Person(name) {
	
	this.name = name;
} 

const ana = new Person("Ana")
const ion = new Person("Ion")

Person.prototype.sayHello = function() {
	
	  console.log(`Salut, sunt ${this.name}`)
}

ana.sayHello() //Salut, sunt Ana
ion.sayHello() //Salut, sunt Ion

*/

function Pers(firstname, lastname) {

	 this.firstname = firstname;
	 this.lastname = lastname;
}

//this -> global object

const ob1 = new Pers("John","Fatima")
const ob2 = Pers('Sarah',"Smith")

console.log(ob1)// Pers{firstname: 'John', lastname: 'Fatima'}
console.log(ob2)//undefined

/*

A: Target > Capturing > Bubbling
B: Bubbling > Target > Capturing
C: Target > Bubbling > Capturing
D: Capturing > Target > Bubbling (Correct)

||  <form>
\/
    <div>

     <p>         /\
                 || 

*/

//Care este output-ul?

let number = 0

console.log( number++ ) //posfix
//          0
//returneaza valoarea care este 0
//incrementeaza valoarea care este acum 1

console.log(++number)
//incrementeaza valoarea care este acum 1 si devine 2
//si dupa acea returneaza valoarea number 2

console.log( number )


/*
A: 1 1 2
B: 1 2 2
C: 0 2 2 (CORRECT ANSWER)
D: 0 1 2
*/

function getPersonInfo(one, two, three) {

	 console.log(one)
	 console.log(two)
	 console.log(three)
}

const person = "John"
const age = 20
const abc = "asd"

//valoarea primului argument este intotdeauna un ARRAY de string de valori
getPersonInfo`${person} is ${age} years old`
//getPersonInfo(`${abc} ${person} is ${age} years old`)
//getPersonInfo(abc,person,age)

/*
A:"John" 20 ["", " is ", " years old"]
B:[""," is ", " years old"] "John" 20 //B correct answer
C: "John" ["", " is ", years old"] 20
*/

//tagged template literals
/*
 getPersonInfo(
  [""," is ", " years old"],
  "John",
  20
 )
 Aici este cheia
*/

function checkAge( data ) {

//verifica daca au aceeasi locatie de memorie ; compara by reference

	 if( data === {age: 18} ) {//return False

	 	console.log("You are an adult!")


	 } else if( data == {age: 18} ) { //return False

	 	console.log("You are still an adult!")

	 } else {

	 	console.log("You do not have an age I guess")
	 }
}

checkAge( {age: 18} )

/*
A: You are an adult
B: You are still an adult
C: YOu do not...
*/

function getAge() {

    'use strict'  

	abcd = 20

	console.log( abcd )
}


//getAge()

//
/*
A: 20
B: undefined
C: ReferenceError //
D: TypeError
*/

//the rest paramenter (...abc) 
//un array este un object
function function_name( ...abc ) {
	

	console.log(typeof abc)

	console.log(abc)
}
function_name( 20, 309, 101, 203, "asdsa","asdasd")


/*
*/