Minimal form autosave functionality using vanilla JS

autosave.js

document.querySelectorAll("form").forEach((formEl) => {
  const key = location.pathname + formEl.id;
  const json = localStorage.getItem(key);
  if (json) {
    const data = JSON.parse(json);
    Object.keys(data).forEach((inputId) => {
      formEl.elements[inputId].value = data[inputId];
    });
  } else {
    localStorage.setItem(
      key,
      JSON.stringify(Object.fromEntries(new FormData(formEl)))
    );
  }
  formEl.addEventListener("input", () => {
    localStorage.setItem(
      key,
      JSON.stringify(Object.fromEntries(new FormData(formEl)))
    );
  });
  formEl.addEventListener("submit", () => {
    localStorage.removeItem(key);
  });
});