index.js

function validateCaracters() {
  let caracPermitted = /^[a-z\s\!\?]{0,}$/;
  textToEncrypt.value.match(caracPermitted) ? encrypt() : informInvalid();
}

function informInvalid() {
  show_invalid_input = document.getElementById("if_invalid_input").innerHTML =
    "ⓘ Only lowercase letters and no accents";
}

function encrypt() {
  let changeTxt = {
    a: "ai",
    e: "enter",
    i: "imes",
    o: "ober",
    u: "ufat",
  };
  let textEncrypted = textToEncrypt.value.replace(
    /[aeiou]/g,
    (c) => changeTxt[c]
  );
  let show = (document.getElementById("show_Encrypt").innerHTML =
    textEncrypted);
  textToEncrypt.value = "";
  show_invalid_input = document.getElementById("if_invalid_input").innerHTML =
    "";
}

//OPTION-2-for-decrypt//
function decrypt() {
  let changeTxtBack = textToEncrypt.value
    .replace(/ai/g, "a")
    .replace(/enter/g, "e")
    .replace(/imes/g, "i")
    .replace(/ober/g, "o")
    .replace(/ufat/g, "u");
  let show = (document.getElementById("show_Encrypt").innerHTML =
    changeTxtBack);
  textToEncrypt.value = "";
}

function copyEncrypt() {
  let textToCopy = document.getElementById("show_Encrypt");
  textToCopy.select();
  navigator.clipboard.writeText(textToCopy.value);
}

let show_invalid_input = "";
let textToEncrypt = document.querySelector("#text_To_Encrypt");
// textToEncrypt.focus();//removed for now.11082022
let button_doEncrypt = document.querySelector("#do_Encrypt");
button_doEncrypt.onclick = validateCaracters;
let button_doDecrypt = document.querySelector("#do_Decrypt");
button_doDecrypt.onclick = decrypt;
let button_copyEncrypt = document.querySelector("#copy_Encrypt");
button_copyEncrypt.onclick = copyEncrypt;

// option-1 THIS OPTION does not DECRYPT WORD INTO SHOW TEXTAREA(FIX) or use OPTION-2
// function decrypt() {
//   let changeTxt = {
//     ai: "a",
//     enter: "e",
//     imes: "i",
//     ober: "o",
//     ufat: "u",
//   };
//   let textDecrypted = textToEncrypt.value.replace(
//     /[ai][enter][imes][ober][ufat]/g,
//     (c) => changeTxt[c]
//   );
//   let show = (document.getElementById("show_Encrypt").innerHTML =
//     textDecrypted);
// }