practice_17_javascript

let button = document.getElementById("start");

button.onclick = function() {
  let h1s = document.getElementsByTagName("h1");
  h1s[0].innerHTML = "버튼 눌려짐";

  let p = document.createElement('p');

  p.innerHTML = Math.random();
  p.style.color = "blue";

  document.getElementsByTagName('body')[0].appendChild(p);
}