Array helper method-review

//Array helper methods
//map
//find
//filter
//findIndex
//forEach

//Reduce

// const arr = [1, 2, 3, 4, 5, 6]

// //extra step in default value
// //acc-0 , curr-1 = 1

// //acc - 1 , curr -2 = 3
// //acc - 3, curr - 3 = 6
// //acc- 6, curr- 4 = 10
// //acc-10, curr-5 = 15
// //acc-15, curr-6 = 21
// const result = arr.reduce((acc, curr) => {
//     //logic
//   return acc + curr
// }, 0)

// console.log(result)

//sum of even square

// function sumOfEvenSquare(arr){
//     //filter the even value
//     // const filtered =  arr.filter(num => num % 2 === 0)
//     // console.log(filtered)
//     // // squaring of the value
//     // const squarredArr = filtered.map(num => num ** 2)
//     // console.log(squarredArr)
//     //  summation
//     // const result = squarredArr.reduce((acc, curr) => acc + curr )
//     // console.log(result)

//      const result = arr.filter((num) => num % 2 === 0).map((num) => num ** 2).reduce((acc, curr) => acc + curr)
//   return result

// }

// const arr = [ 2, 3, 4, 5, 6 ]
// console.log(sumOfEvenSquare(arr))

// Use the given array of product objects below, each with their name, price, and quantity sold. Additionally, you are given a tax rate as a percentage. Write a function called `calculateTotalSalesWithTax` that takes in an array of product objects, along with the tax rate (8%), and returns the total sales amount including tax.

// const products = [
//   { name: 'Apple', price: 0.5, quantity: 10 },
//   { name: 'Banana', price: 0.3, quantity: 20 },
//   { name: 'Orange', price: 0.6, quantity: 15 },
// ]

// function calculateTotalSalesWithTax(products, taxRate) {
//   // calculate total product price
//   const totalPrice = products.reduce((acc, curr) => {
//     const price = acc + curr.price * curr.quantity
//     return price
//   }, 0)
//   console.log(totalPrice)
//   //calculate total Tax
//   const calulatedTax =( totalPrice * taxRate) / 100

//   console.log(calulatedTax)
//   //sum up the total price with tax
//   return totalPrice + calulatedTax
// }

// console.log(calculateTotalSalesWithTax(products, 8))

// function findMissingLetter(arr) {
//   if (!Array.isArray(arr)) return ''
//   if (arr.length < 2) return ''
//   let start = arr[0].charCodeAt(0)
//   console.log(start)
//   const missingCharCode = arr.map((char) => char.charCodeAt(0))
//   console.log(missingCharCode)
//   const findMissingChar = missingCharCode.find((current) => {
//     console.log(current)
//     if (current - start > 1) {
//       return true
//     }
//     start = current
//     return false
//   })

//   console.log(findMissingChar)

//   const result =
//     missingCharCode.length >= 2 ? String.fromCharCode(findMissingChar - 1) : ''
//  return result
// }

function findMissingLetter(arr) {
  let start = arr[0].charCodeAt(0)
  console.log(start)

  const missingCharCode = arr.reduce((missing, char) => {
    const current = char.charCodeAt(0)
    if (current - start > 1 && missing == null) {
      missing = start + 1
    }

    start = current

    return missing
  }, null)

  console.log(missingCharCode)

  return missingCharCode ? String.fromCharCode(missingCharCode) : ''
}

findMissingLetter(['a', 'b', 'c', 'e', 'f'])