scripts.js

function calculateTip(event) {
  event.preventDefault();

  let bill = document.getElementById("bill").value;
  let qualityService = document.getElementById("qualityService").value;
  let numOfPeople = document.getElementById("people").value;

  if ((bill == "") | (qualityService == 0)) {
    alert("Por favor, preencha os campos!");
    return;
  }

  if ((numOfPeople == "") | (numOfPeople <= 1)) {
    numOfPeople = 1;
    document.getElementById("each").style.display = "none";
  } else {
    document.getElementById("each").style.display = "block";
  }

  let total = (bill * qualityService) / numOfPeople;
  total = total.toFixed(2);
  document.getElementById("tip").innerHTML = total;
  document.getElementById("totalTip").style.display = "block";
}

document.getElementById("totalTip").style.display = "none";
document.getElementById("each").style.display = "none";

document.getElementById("tipsForm").addEventListener("submit", calculateTip);