7.Scope closure hoisting destructuring rest spread

// const person = {
//   firstName: 'samim',
//   lastName: 'fazlu',
//   age: 30,
//   fullName() {
//     return this.firstName + '-' + this.lastName + '-' + this.age
//   },
// }

//pulling out of property from object or array
// const { firstName, fullName, ...restValues } = person
// console.log(fullName)
// // console.log(fullName.call(person))
// // console.log(myAge)
// console.log(restValues)

// const arr = ['samim', 'Fazlu', 30]
// // const [fName, , age] = arr
// const [fName,... restArr] = arr
// console.log(arr[0])
// console.log(restArr)
// console.log(fName, age)

// console.log(person.firstName)
// console.log(person.lastName)
// console.log(person.age)
// console.log(person.fullName)

//rest (...) Destructuring
//spread(...)

// const personWithProfession = {
//   ...person,
//   profession: 'App Developer',
// }

// console.log(personWithProfession)

// const newWdArr = [...arr, 'web developer']
// console.log(newWdArr)

// function printPerson(fName, lName, age) {
// }

// const person = {
//   firstName: 'samim',
//   lastName: 'fazlu',
//   age: 30,
// }

// printPerson('samim', "hasan")

//scope (the world where data is defined and can be accessed)
//var (functional scope, global scope)
//let, const(block scope {}, global scope)
//if variable is declared globally with var or let or const keyword it can be accessed any part of the script

// var a = 10

// function b() {
//   var c = 20
// //   console.log(a)
//   console.log(c)
//   return c
// }
// b()

// b()
// console.log(a)
// // console.log(c)

//if let ,const  is declared inside block{} then it will be available only in inside the block{}
//otherwise it will be considered as global(global variable can be accessed from anywhere)
//loop gotcha

// const d = 40
// {
//   var e = 50
//   const blockVar = 30
//   console.log(blockVar)
// // console.log(d)
// }

// console.log(e)
// console.log(blockVar)

// for (let i = 0; i < 10; i++) {
//   console.log(i)
// }

// console.log(i)
//scope chain
// From children scope you can access parent scoped variable (children can access parent property) -scope chain
// const a = 20
// function showScope() {
//    const a = 10
//   {
//     const a = 100
//     console.log(a)
//     const b = 20
//     console.log(b)
//   }
//   console.log(a)
//   console.log(b)
// }

// showScope()

//closure scope
//variable scope is limited to it's function lifespan
//After function execution is over(function running) it's scoped variable is vanished except the variable reference from inner function

// function sum(num1) {
//   num1 = 3
//   return (num2) => {
//     return num1 + num2
//   }
// }

// const innerFunc = sum(3)
// console.log(innerFunc(4))

//Hoisting (lifting up variable and accessing in different part)
// console.log(a)
// console.log(func())
// console.log(hello())

// const a = 10
// const func = function () {
//   console.log('Hi')
// }

//   console.log(func())
// function hello() {
//   return 'hello'
// }

//preparation phase
//function declaration (statement) in memory
//variable declaration (memory)
//variable value is not set
// var a;
//var func
//function hello(){
//     return 'hello'
// }

//execution phase
// variable value assign
//calling..
// console.log(a) //undefined
// console.log(func())
// console.log(hello()) //'hello'
//a = 10