JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="ja">
  <head>
    <meta charset="UTF-8">
    <title>Sample Code</title>
    <link rel="stylesheet" href="css\styles.css">
  </head>
    <body>
      <input type="button" id="button" value="ボタン">
      <p id="display"></p>
      <script src="js\main.js"></script>
    </body>
</html>

JavaScript

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

function message() {
  display.textContent = "3秒が経過しました。";
}

button.addEventListener("click", () => {
  setTimeout(message, 3000);
});