form-validation

[roshlarosh]

You can implement some form validation by applying existing method: validity.valueMissing
you can either have a separate file with all the form validation or have it in your index.js file

const username = document.getElementById("new-username");
const userErr = document.getElementById("userErr");

let checkUser = () => {
  if (username.validity.valueMissing) {
    displayErr(userErr, "Please enter a username");
  } else {
    displayErr(userErr, "");
    return true;
  }
};
function displayErr(errElem, errMsg) {
  errElem.innerText = errMsg;
}

username.addEventListener("focusout", checkUser);