const element = document.getElementById（ "myElement"）;
element.style.display = "none";

setimeout（function（）{
  element.style.display = "block";
}、3000）;// 3000ミリ秒= 3秒
const element = document.getElementById("myElement");
element.style.display = "none";

setTimeout(function() {
  element.style.display = "block";
}, 3000); // 3000 milliseconds = 3 seconds