Js

Question 1

How can we deleet everything in chrome Console ?

Answer 1

type: clear
or
ctrl + k

Question 2

How to get to console directly ?

Answer 2

command + option + j
or
got to view => developer=> javascript console

Question 3

+

Answer 3

addition

Question 4

-

Answer 4

subtraction

Question 5

*

Answer 5

Multiplication

Question 6

/

Answer 6

Division

Question 7

%

Answer 7

Modulo

Question 8

what is prder operations ?

Answer 8

PEMDAS

Question 9

what is PEMDAS

Answer 9

parantheses, exponents, Multiplication, division, addition, substraction

Question 10

how can i recall previous run lines ?

Answer 10

with up/down arrow

Question 11

how tp make a comment in Js ?

Answer 11

with //

Question 12

modulo known also as ?

Answer 12

remeinder operator

Question 13

how to to pronaunce modulo ?

Answer 13

madulo

Question 14

what means 9%2

Answer 14

it means two goes into nine how many time as a whole number, and how much will be remain ?
9%2 = 1

Question 15

modulo ist commen to use where ?

Answer 15

to determine if a number is even or odd

Question 16

how to write 2²?

Answer 16

2**2

Question 17

what Nan stand for ?

Answer 17

not a number

Question 18

NaN consider as what is js ?

Answer 18

consider as a number

Question 19

0/0 =

Answer 19

NaN

Question 20

how to check js consider an ellement as what ?

Answer 20

with command typeof
ex: typeof 4 = number

Question 21

what is variable ?

Answer 21

it is the way of giving some name to a value and sorting it using js.

Question 22

how we make a variable ?

Answer 22

let year =. 1985;

Question 23

how to update the value of a variable ?

Answer 23

imagine we have let numApple = 4;
- write it again : numApple = 5;
or
-numApple = numApple + 1
or
-numApple +=5
-numApple -=5

Question 24

• if i had totalFruits= numApple + num Orange in previouse liene and than I updated numApple, how can i update totalFruits value ?

Answer 24

just write totalFruits= numApple + num Orange again

Question 25

score ++; =

Answer 25

score+=1;

Question 26

score–; =

Answer 26

Score-=1;

Question 27

what Const stand for ? and what is it ?

Answer 27

Constant, it is a value that does not change

Question 28

What is VAR ?

Answer 28

BEFORE LET AND CONST, VAR was the only way of Declaring variables. these days it is not commen to use.

Question 29

How many optons do we have for a Boolean value ?

Answer 29

two, true or false

Question 30

Whats is Booleann use to ?

Answer 30

to store yes or no, True or false
Ex numPuppies = false;

Question 31

js hard ruls:

Answer 31

-we cant have space between our name
- we cant have number at begining of my name
- the Names are case sensitiv
these names can contain also $ and

Question 32

what is the other name for Number ?

Answer 32

identifier

Question 33

what is the name of this type of typing numberOfBoys ?

Answer 33

camel cased

Question 34

by Boolean it is better how to name them ?

Answer 34

instead of gameOver = True;
isGameOver

Question 35

What is String ?

Answer 35

It textual information, they reprecents text, and they must be wrapped in quots.
let username = “pouya”;
- we can have space in between
-we can have $
-we can have numbers
-it can be zero character lang
- we can use one string inside another string
“I´love´you “
- we cant do like that
“I”love”you “

Question 36

string index start with which number ?

Answer 36

0

Question 37

How can I access indexes of my string ?

Answer 37

let animal = “cat”;
animal[1] = “a”

Question 38

what is concatenation ?

Answer 38

“lol”+”lol”= “lollol”

Question 39

a combination of number and string is :

Answer 39

string

Question 40

msg.toUppercase ()
what is toUpperCase () ?

Answer 40

it is a method

Question 41

with which method can we upper case our string ?

Answer 41

.toUpperCase ()

Question 42

with which method can we lower case our string ?

Answer 42

.toLowerCase ()

Question 43

what is trim Method ?

Answer 43

it is going to trim off any whitespace at the begining of a string or at the end.

Question 44

we can chain methids together

Answer 44

.

Question 45

what is arguments ?

Answer 45

are inputs that we can pass into the method to alter how they behave
ex: searchFor(“a”) “a” is an argument.

Question 46

what is indexOf method?

Answer 46

its going to give us the string index and positional number where a given argument occurs in a string.

Question 47

what is slice method?

Answer 47

it can accept more than one argument .
it is going to extract or slice a portion of a string and it returns it or give it to us as a new string.
let msg = “haha that is so funny!”
msg.slice(5) =”that is so funny!”
or
“haha that is so funny!”.slice(5)
or
msg.slice(5, 10)

Question 48

what is replace method?

Answer 48

msg.replace (“haha”,”lol”)

Question 49

what is repeat method?

Answer 49

“lol”.repeat(10) = “lollollollollollollollollollol”

Question 50

what is Template Literal ?

Answer 50

these Templates allows us to create strings where we can embed an expression inside the string and that expression will be evaluated and turned into a string.
´I counted ${x+y} sheep´

Question 51

Template Literals only works with back ticket, what is back ticket ?

Answer 51

´´

Question 52

what is the pronaunciation for null

Answer 52

nol

Question 53

what is undifined

Answer 53

it is the way of js sayin, I dont know. I dont know what do you want.

Question 54

what is null

Answer 54

it is a value we can set for a variable

Question 55

what is The Math object ?

Answer 55

it´s a collection of properties and methods that have to do with math in some way.

Question 56

what is math.floor ?

Answer 56

it will take a number with a decimal and chop of that decimal, so it´s not rounding.

Ex: math.floor (23.9999999) = 23

Question 57

Math.ceil (34.1) =

Answer 57

35

Question 58

what is math.random ()

Answer 58

it will give us random numbers between 0 an 0.999999999

Question 59

make random number beween 1 and 10

Answer 59

Math.floor(math.random()*10)+1

Question 60

>

Answer 60

greater than

Question 61

<

Answer 61

less than

Question 62

> =

Answer 62

greater than or equal

Question 63

==

Answer 63

equality

Question 64

!=

Answer 64

not equal

Question 65

===

Answer 65

strict equality

Question 66

!==

Answer 66

strict non equality

Question 67

what is unicode ?

Answer 67

underlying code of every character

Question 68

what is the diffrence between == and ===

Answer 68

===checks the type too

Question 69

how we print our arguments in js ?

Answer 69

console.log()

Question 70

alert

Answer 70

it gonna pop up an alert user

Question 71

prompt

Answer 71

it is gonna accept an argument

Question 72

how do i connect my html and js

Answer 72

I will write

in the end of my body in html

Question 73

what is if statement ?

Answer 73

my code will run if given condition is true
let rating =3;
if (rating===3){
console.log(“You are a super star”);
}

Question 74

what is else if statement ?

Answer 74

if the if part was false, then maybe try this other thing
et rating =3;
if (rating===3){
console.log(“You are a super star”);
}
else if (rating===2){
console.log(“Meets Expectitations”)
}
* we can have as many else if as we want

Question 75

is the order of else ifs matter ?

Answer 75

yes, so much

Question 76

what is else statement ?

Answer 76

else going to be the last part. it is always last piece.
if (rating===3){
console.log(“You are a super star”);
}
else if (rating===2){
console.log(“Meets Expectitations”)
}
else {
console.log(“Meh”)
}

Question 77

every single value in js have truthy exept

Answer 77

1- false
2- 0
3- “” (empty string
4- null
5- undifined
6-NaN

(these are falsy)

Question 78

what is logical operators ?

Answer 78

logical operators are operators that allow us to combine diffrent expressions

Question 79

logical operators => and

Answer 79

&&

Question 80

logical operators=> or

Answer 80

II

Question 81

logical operators=> not

Answer 81

!

Question 82

in order to logical operator ´and´ gonna be true, what is important ?

Answer 82

the left and right side must be true

Question 83

in order to logical operator ´or´ gonna be true, what is important ?

Answer 83

it doesnt need both part to be true, in order whole thing to be true, it just need one part to be true

Question 84

what does ´not´ logical operator ?

Answer 84

it is going to negate the value, if its true it will change it to false, if its fals it change it to true

Question 85

what is Arrays ?

Answer 85

-it is a collection of values.
-it is an ordered collection of values
- it is an array: []

Question 86

imagine we have this array:
days[1] = “Tursday”
How can I get “T” from it ?

Answer 86

days [1][1]

Question 87

how can we update an array ?

Answer 87

by typing it again with the new value

Question 88

how to update a string ?

Answer 88

it is not possible

Question 89

what does ´push and pop ´

Answer 89

it allow us to add and remove from the end of an array

Question 90

How to use push ?

Answer 90

let movie = [“tom”,”jerry”]
movie.push (“alice”,”elford”)

Question 91

how to use pop ?

Answer 91

movie.pop() and it will remove an element from the end

Question 92

what is shift and unshift ?

Answer 92

shift removes from the beginning of an array
unshift remove add to beginning

Question 93

how we use shift ?

Answer 93

movie.shift()

Question 94

How to use unshift ?

Answer 94

movie.unshift (“jordan”,”petter”)

Question 95

what is concat ?

Answer 95

we mix two array and become the third array

Question 96

How do we use concat ?

Answer 96

let cat = [“kitty”,”blue”]
let dog =[“dokme”,”chakme”]
cat.concat(doge)

Question 97

what is includes ?

Answer 97

it show us if an array contain a value in true or false.
cat.includes(“party”)

Question 98

what is a Reverse ?

Answer 98

it is going to reverse an array.

Question 99

what else happens when i use reverse ?

Answer 99

the original array also will be modified

Question 100

what are slice and splice ?

Answer 100

slice is the way of copying a slice of an array and
splice is going to change content of an array by removing or replacing existing elements or adding new ellements in place

Question 101

how to use slice ?

Answer 101

colorsd.sliche(3 )
it will start from 3 toward
colorsd.sliche(3, 5 )
it will take slice between index 3 and 5

Question 102

how to use splice ?

Answer 102

colors.splice (5,1)
it will remove one element at index 5
colors (5, 0, “red”)
at index of 1 it wiill remove nothing and just add red after that

Question 103

what is sort ?

Answer 103

if we just call array.sort() , it will change it to a string

Question 104

How to update a Const ?

Answer 104

it is not possible in normal way.
- it is possible if we mix it with array
ex:
const nums =. [1, 2, 3]

Question 105

imagine I have
const gane =[[“x”,”o”,”x”],[“o”,”null”,”x”],[“o”,”o”,”x”]]
how can i access null ?

Answer 105

game[1][1]

Question 106

js objects are made from what ?

Answer 106

key and value
let comment = {
username: “pouya”,
age : 30
tags: [ “#A”, “#B”, “#c”]
};

Question 107

how can we access pouya in this js object ?
key and value
let comment = {
username: “pouya”,
age : 30
tags: [ “#A”, “#B”, “#c”]
};

Answer 107

comment[“username”]
or
comments.username

Question 108

I have
const midterm {daniel: 79, susane: 89, marta: 70}
How can i update susane midterm ?
and how can i add a mark for azra ?

Answer 108

midterm.susane = 95;
midterm.azra = 80

Question 109

write a for loop

Answer 109

for (let i = 1; i++){
console.log(i);
}

Question 110

write a infinate loop

Answer 110

for (let i = 20; i>= 0; i++) {
console.log(i)
}

Question 111

write loop for
const animals = [ “lions”,”cats”,”dogs”];
I expect the resault will be
0 “lions”
1”cats”
2”dogs”

Answer 111

for (let i = 0; i<animals.length; i++) {
console.log(i, animals[i]);
}

Question 112

which alphabet do we usualy use for for loop?
which alphabet do we usualy use for first nested for loop ?
which alphabet do we usualy use for second nested for loop ?
which alphabet do we usualy use for third nested for loop ?

Answer 112

1- i
2- j
3- k
4- m
5- .
.
.
.

Question 113

We have
const seatingChart = [
[“kristen”,”erik”,”namita”],
[“geoffery”,”julia”,”antonio”,”kevin”],
[“yuma”,”sakura”,”jack”,”erika”]
]
how can we print out every name ?

Answer 113

for (let i = 0; i <seatigChart.length; i++) {
const row = seatigChart[i];
console.log(´ROW ${i+1}´)
for (let j = 0;vj <row.length; j++){
console.log([j])
}
}

Question 114

what is while loop

Answer 114

it has only one single condition and as long as this condition is true, our loop will continue to run.

Question 115

write a while loop

Answer 115

let num = 0;
while (num<10) {
console.log(num);
num++;
}

Question 116

what is the break keyword in js

Answer 116

-it usually use in while loop
-it causes the loop to exit immediately

Question 117

what is for… of

Answer 117

for…of allows you to iterate over the values of an iterable object like arrays, strings, maps and sets.
Syntax: ´for (const value of iterable) { // code }´
Use ´for…of´ when you need to iterate over the values of an iterable object, rather than the index.

Question 118

can use for…of only with what ?

Answer 118

only with iterable object

Question 119

what is for… in

Answer 119

-it is pretty uncommen these days.
-it will give us only key in the object

Question 120

what shold i di by for in if I want for … in too ?

Answer 120

for (let person in testScores){
console.log()´${person}scored ${testScores[person]}´);
}

Question 121

how many steps do we have to write an object ? what are them?

Answer 121

two steps:
1- define the function
2- execute it

Question 122

write a sample function

Answer 122

function functionName(){
//do something
}
funcName()

Question 123

what is argument ?

Answer 123

argument in js is fancy way of saying inputs to a function
function greet(firstName) {
console.logi(´firstName is: ${firstName}´)
}

====>firstName is an Argument

Question 124

write a function with multiple arguments

Answer 124

function greet(firstName,lastName) {
console.log(´Hey there, ${firstName}!´)
}

Question 125

What is Return ?

Answer 125

to have capturable value from function we need Return.
so instead of :
function add(x,y){
console.log(x+y)
}
we write:
function add(x,y){
return x+y;
}
console.log(x+y)

Question 126

what should be know about return keyword ?

Answer 126

-return keyword actually stops the execution of our function so wherever I have something aftewards, like console.log() , this line will not run
-we can only return a single value