• " for printing double quotes in a string
• \ for backslash
• ? For question mark
• \n new line
• \t tab
• \b backspace

String variable cannot be mutated but can be reassigned with new string

• let : block scope variable
• const : same as let and prevents mutation
• var : accessible everywhere

const array cannot be reassigned with new string but can be mutated

To completely prevent mutation we use Object.freeze() method

// Const variable should be allcaps
const MYCONST= { pi : 3.14}

Object.freeze(MYCONST)

... Three dots

Var f = Function(...args) { //code} 

All the arguments will now be clubbed into an array.

Spread operator for making a copy

Arr1= ["a" , "b"]
Arr2 = [...arr1]; 

More or less same as unpacking

[a,b] = [b,a] // swapping
const [z,x, , y] = [1,2,3,4,5] // 3 is skipped

Setters and getters in js are defined same as functions but are used as properties. There was no ( ) used while calling of these properties.

Setter is used to set the values of properties getter is used to get the values of properties of an object

Definition of setters and getters

Set property_name() {
//Code }

Same with get
Both are Used in a class

Global context : all about collecting what has been written in the program. has window object in it

Execution context : when program is in execution line by line the execution blocks are stacked over global context. So in js when a function is called before its definition there's no error because global context is already knows about it.

Two things that global context does with functions and variables

Function declarations are scanned and made available. Variable declarations are scanned and made undefined.

One liner arrow functions : Const f = par => { //code } F is used as function name while calling Par is the parameter If multiple parameters are used then syntax is (par1,par2) '

. every ( ) method is used on arrays which return true if something is true for each element of array

Arr.every(iseven) //iseven is a user-defined function. Remember no parenthesis