first_time_do_convert.js

let firstInput = document.querySelector('#firstInput')
let secondInput = document.querySelector('#secondInput')
const btn = document.querySelector('button');

let arr = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
let length = arr.length


btn.addEventListener('click', function () {
  // console.log(firstInput.value[0]);
  // console.log(firstInput.value[1]);
  for (let i = 0; i < length; i++) {

    if (firstInput.value[0] === arr[i]) {
      // console.log('Input1 vs arr1', firstInput.value[0], arr[i])
    }

    for (let j = 0; j < length; j++) {
      if (firstInput.value[1] === arr[j]) {
        // console.log('Input2 vs arr2', firstInput.value[1], arr[j])
        for (let k = j; k < length; k++) {
          console.log(`third loop: ${firstInput.value[0]}${arr[k]}`)
        }
      }
      // console.log(`i+j:${arr[i]}${arr[j]}`)
    }
    break
  }

  // console.log(arr.indexOf(secondInput.value[0]))
  // console.log(arr.indexOf(firstInput.value[0]))
  for (let i = arr.indexOf(firstInput.value[0]) + 1; i < arr.indexOf(secondInput.value[0]); i++) {
    // console.log('second for:', i, arr[i])

    for (let j = 0; j < arr.length; j++) {
      console.log(`i+j:${arr[i]}${arr[j]}`)
    }
  }

  for (let i = 0; i < length; i++) {

    if (secondInput.value[0] === arr[i]) {
      console.log('Input3 vs arr1', secondInput.value[0], arr[i])
    }

    for (let j = 0; j < length; j++) {
      if (secondInput.value[1] === arr[j]) {
        // console.log('Input4 vs arr2', secondInput.value[1], arr[j])
        // console.log(typeof arr.indexOf(secondInput.value[1]))
        for (let k = 0; k <= arr.indexOf(secondInput.value[1]); k++) {
          console.log(`third2 loop: ${secondInput.value[0]}${arr[k]}`)
        }
      }
      // console.log(`i+j:${arr[i]}${arr[j]}`)
    }
    break
  }
});