app.js

function convert() {
  let to_convert = document.getElementById("to_convert").value;
  to_convert = parseFloat(to_convert);
  let x = document.getElementById("x").value;
  let y = document.getElementById("y").value;

  // Validate provided inputs
  if (x == y || x < 2 || y < 2 || isNaN(to_convert)) {
    alert("HUH!? -_-");
  }

  // Organising results
  let res;
  if (x == 10) {
    res = Con_Dec_to_Basey(to_convert, y);
  } else if (y == 10) {
    res = Conv_Basex_to_Dec(to_convert, x);
  } else {
    res = Conv_Basex_to_Dec(to_convert, x);
    res = Con_Dec_to_Basey(res, y);
  }

  // Visualizing results
  let final = document.getElementById("res");
  final.value = res;
}

function Con_Dec_to_Basey(to_convert, y) {
  // Converting Integral part
  let integral_part = parseInt(to_convert);
  let res = [];
  while (parseInt(integral_part) != 0) {
    integral_part /= y;
    let element = (integral_part - parseInt(integral_part)) * y;
    res.unshift(parseInt(element));
  }

  // Converting Decimal part
  let decimal_part = to_convert - parseInt(to_convert);
  let res_dec = [];
  let percision = 10; // Special case for binary
  while (decimal_part != 0) {
    decimal_part = (decimal_part - parseInt(decimal_part)) * y;
    // Special case for binary
    if (res_dec.includes(parseInt(decimal_part))) {
      if (percision == 0) {
        break;
      }
      percision -= 1;
    }
    res_dec.push(parseInt(decimal_part));
  }

  let final;
  if (res_dec.length == 0) {
    final = res.join(" ");
  } else {
    final = res.join(" ") + " . " + res_dec.join(" ");
  }
  return final;
}

function Conv_Basex_to_Dec(to_convert, x) {
  let i = 0;
  let res = 0;

  let integral_part = parseInt(to_convert)
    .toString()
    .split("")
    .reverse()
    .join("");
  for (number of integral_part) {
    let element = parseInt(number) * x ** i;
    res += element;
    i += 1;
  }

  let decimal_part = to_convert.toString().split(".")[1];
  if (decimal_part) {
    i = -1;
    for (decimal of decimal_part) {
      let element = parseInt(decimal) * x ** i;
      res += element;
      i += -1;
    }
  }

  return res;
}

function copyres() {
  let final = document.getElementById("res");
  final.select();
  final.setSelectionRange(0, 99999);
  document.execCommand("copy");
}