Как в этом скрипте реализовать localStorage?

const termsOfUse = document.querySelector(".terms_of_use");
const iAgree = document.querySelector(".i_agree");
const main = document.querySelector(".main");
const test = 50;

setTimeout(function() {
  termsOfUse.style.transform = "translateY(0%)";
  termsOfUse.style.position = "fixed";
  termsOfUse.style.top = "0" + "px";
}, 10);

function appearance() {
  let blockHeinght = termsOfUse.getBoundingClientRect().height;
  main.style.transform = "translateY(" + blockHeinght + "px)";

  console.log(termsOfUse.getBoundingClientRect().height);
}
appearance();

function back() {
  termsOfUse.style.transform = "translateY(-100%)";
  termsOfUse.style.position = "";
  termsOfUse.style.top = "0" + "px";

  let blockHeinght = termsOfUse.getBoundingClientRect().height;
  main.style.transform = "translateY(" + "0" + "px)";

  console.log(termsOfUse.getBoundingClientRect().height);
}