YDKJS get started

Question 1

what is a transpiler?

Answer 1

it is a tool that converts js code to an old compatible version

Question 2

what is an example of a transplier?

Answer 2

babel

Question 3

what do u use to be compatible with old syntax?

Answer 3

transpiler

Question 4

what do u use to be compatible with new methods?

Answer 4

polyfill

Question 5

is js interpreted?

Answer 5

kind of but more of a compiled language as we know static errors before actually running the code which means the script is parsed before it’s ran

Question 6

how does js files share their funcionality?

Answer 6

1 - global scope

2 - modules

Question 7

what are the types of js values?

Answer 7

1 - primitive

2 - objects

Question 8

what are the primitive types of js?

Answer 8

1 - strings
2 - int
3 - bigInt
4 - undefined
5 - null
6 - symbol

Question 9

what is the difference between var and let?

Answer 9

let is block scoped

Question 10

what happens when you change the value inside a CONST array?

Answer 10

you can change the value but you cannot change the array itself

Question 11

what is the difference between function declaration and function expression?

Answer 11

1 - function declaration happens during compile time
function name(){
}

2 - function expression happens during interpretation time
var
const
let
             name = function (){
}

Question 12

how does js treat functions?

Answer 12

as a sub-type of object namely ‘function’ and can be assigned

Question 13

what does === mean?

Answer 13

check for type and value

Question 14

what are the values that === lies about?

Answer 14

1 - Nan === Nan
2 - 0 === -0 -> checks for object.is()
3 - object types

Question 15

why does === does not work for objects?

Answer 15

because it checks for the reference meaning the address no the values inside the object

Question 16

what does == do?

Answer 16

changes the type in some cases before comparison

Question 17

what does == do for number and string?

Answer 17

changes the type of string to it’s number and compare

Question 18

what does == do for two strings?

Answer 18

checks them alphabetically

Question 19

what is … used for?

Answer 19

spreading and gathering

for spreading an array it returns another array of each value

var greeting = "Hello world!";
var chars = [ ...greeting ];
chars;
// [ "H", "e", "l", "l", "o", " ",
// "w", "o", "r", "l", "d", "!" ]

Question 20

what is a closure?

Answer 20

Closure is when a function remembers and continues to access variables from outside its scope, even
when the function is executed in a different scope.