<button id="button_A">Press me</button>
<h3 id="heading_A"></h3>

const buttonA = document.querySelector("#button_A");
const headingA = document.querySelector("#heading_A");

buttonA.onclick = () => {
  const name = prompt("What is your name?");
  alert(`Hello ${name}, nice to see you!`);
  headingA.textContent = `Welcome ${name}`;
};