javascript.html

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Simple Web Page</title>
    <link rel="stylesheet" type="text/css" href="simple.css">
  </head>
  <body>
    <h1 id="title">This is a Simple Web Page</h1>

    <p>
      HTML includes both content and instructions to the browser determining how
      the content should look. For example, the following items should be in a
      numbered list:
    </p>

    <ol>
      <li>First</li>
      <li>Second</li>
      <li>Third</li>
    </ol>

    <p>
      <strong>Here is some bold text.</strong> <i>And this in italics.</i>
    </p>
  </body>
  <script>
    setInterval(function () {
      var x = document.getElementById("title")
      if (x.style.visibility === "visible") {
        x.style.visibility = "hidden"
      } else {
        x.style.visibility = "visible"
      }
    }, 1000)
  </script>
</html>