// Question 1: Create an Array from 0...100 without using traditional For-loop
function arrayList(){
  var i=0;
  return new Array(101).fill(0).map(()=>i++)
}

// Question 2: Create an Array of only even numbers from the above array
function TwoOnly(){
  return arrayList().filter(x=>x%2 === 0)
}


// Create a function that returns a Promise which returns the
// square of only even numbers and
// throws an error if an odd number is passed
function tell(x){
  return new Promise((resolve,reject)=>{
    if(x%2 == 0){
        resolve(x*x)
    }else{
      reject("Odd Number")
    }
  })
}

// Question 3: create an array of even squares using the previous array
// direct invocation is important to see if the
// candidate understands Arrow functions correctly.
function squareOfEven(){
    return TwoOnly().map((x)=>x*x)
}


// Question 4: Sum of all the squares from the above array of Even Squares
function totalSum(){
  return squareOfEven().reduce((initial,val)=>val=val+initial,0)
}

// Question 5: Call the above square Promise function with all numbers from 0-100
// and ensure that the errors are not thrown
// then print the following:
// 1. Number of errors
// 2. The resultant array
// 3. Number of objects in the resultant array

var arr=arrayList();
var promiseArray=[]
for(i=0;i<arr.length;i++){
	promiseArray.push(tell(arr[i]))
}
var num=0
var i=0;
Promise.all(promiseArray).then((x=>{
 	return new Promise((resolve,reject)=>{
		x.forEach((y)=>{
		if(y==null){
            i++;
		}
		})
	resolve(i)
	})
}))

Promise.all(promiseArray).then((x=>{
 	console.log("resultant array",x)
}))



// Q1: Create a template string of a button HTML Element. Save the title
// for the button in a separate var and use it in the button correctly.
function createButton(){
var buttonTitle = "submit" ;
return `<button>${buttonTitle}</button>`;
}


// Q2: Create a function that returns a list element (<li>) HTML
// use this function to create a ordered list HTML structure of numbers from
// 1-30 without breaking the template string invocation i.e. usage of += is disallowed.
function getOrderedList(){
var len  = 30 ;
var return_str = "" ;
return_str = return_str.concat('' , '<ol>')
for(let i = 1; i <= len ; i++){
return_str = return_str.concat('' , `<li>${i}</li>`)
}
return_str = return_str.concat('\n' , '</ol>')
return return_str
}

// Q3: Now only print the even numbers. Again, breaking the template string
// invocation is disallowed
function getEvenOrderedList(){
var len  = 30 ;
var return_str = "" ;
return_str = return_str.concat('' , `<ol>`)
for(let i = 1; i <= len ; i++){
if(i%2 == 0) return_str = return_str.concat('' , `<li>${i}</li>`)
}
return_str = return_str.concat('\n' , `</ol>`)
return return_str
}


// Q4: Create a promise that simulates a delay of 1-3s randomly. Create an array of
// 10 such promises. Only print the output when all promises have been resolved
var len_of_arr = 10 ;
var promise = [] ;
var time_arr = [1,2,3] ;
for(let i = 0 ; i < len_of_arr ; i++){
promise.push(new Promise(function(resolve,reject){
setTimeout(function(){ resolve(i) }, time_arr[Math.floor(Math.random() * time_arr.length)]*1000);
}))
}

Promise.all(promise).then(function(resp){
console.log(resp)
})