Persist / restore form data using localStorage

persist-restore-form-data.js

// Persist data:
localStorage._formData_ = JSON.stringify(Array.from(document.forms[0].querySelectorAll('input')).map((el) => el.value));

// Restore data:
_formData_ = JSON.parse(localStorage._formData_) || [];
Array.from(document.forms[0].querySelectorAll('input')).forEach((input, id) => {
  input.value = _formData_[id];
  var event = document.createEvent("HTMLEvents");
  event.initEvent("input", true, true);
  input.dispatchEvent(event);
});