index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Codec generator</title>
  </head>

  <body>
    <main></main>
    <script src="./build/main.js"></script>
    <script>
      var storedModel = {};

      try {
        storedModel = JSON.parse(localStorage.getItem("model"));
      } catch (e) {
        // Either the parse failed, or localStorage is inaccessible,
        // or we have no model. It's fine. Whatever.
      }

      var app = Elm.Main.init({
        node: document.querySelector("main"),
        flags: storedModel,
      });

      app.ports.save.subscribe((model) =>
        localStorage.setItem("model", JSON.stringify(model))
      );
    </script>
  </body>
</html>