Exit Intent Waitlist Popup: How to Build One Without a Plugin

A visitor reads your pricing section, moves the cursor to the tab bar, and is gone. You never learn what they wanted, and you never got an email. An exit intent popup is a last, single chance to ask for that email as the cursor heads for the exit.

It is also easy to get wrong. The desktop signal is one event listener, the mobile signal does not exist, and a popup that fires twice per visit trains people to resent you. This guide builds the whole thing with a native <dialog> and one SDK call, no plugin.

Build the Dialog

The modal itself is covered in How to Trigger a Waitlist Modal From Any Button: keep the markup permanently in the DOM and reveal it with showModal(). This version builds the form yourself with the SDK, so it works even when your hero already holds the one allowed waitlist widget.

<dialog id="exit-modal">
  <form id="exit-form">
    <h2>Before you go</h2>
    <p>Get early access and a link to move up the list.</p>
    <input type="email" name="email" placeholder="you@company.com" required />
    <button type="submit">Join the waitlist</button>
    <button type="button" id="exit-close">No thanks</button>
  </form>
  <p id="exit-done" hidden>You are on the list.</p>
</dialog>

<script src="https://operatorstack.dev/os.js" data-project="pk_your_project_key"></script>

Detect the Exit

Exit intent on desktop means the cursor left the page through the top edge. Sides and bottom do not count: a cursor leaving toward the scrollbar is not heading for the tab bar.

<script>
  const modal = document.getElementById("exit-modal");
  const KEY = "os_exit_shown";

  function showExit(trigger) {
    if (sessionStorage.getItem(KEY)) return;
    if (window.OperatorStack && window.OperatorStack.isSignedUp()) return;
    sessionStorage.setItem(KEY, "1");
    modal.showModal();
    window.OperatorStack.trackEvent("exit_popup_shown", { trigger });
  }

  document.documentElement.addEventListener("mouseleave", (e) => {
    if (e.clientY <= 0) showExit("mouseleave");
  });
</script>

Three guards run before the dialog opens. The sessionStorage flag caps it at one showing per session. isSignedUp() skips anyone who already joined. Setting the flag before showModal() means a rapid second event cannot reopen it.

Submit With the SDK

<script>
  const form = document.getElementById("exit-form");

  form.addEventListener("submit", async (e) => {
    e.preventDefault();
    try {
      await window.OperatorStack.joinWaitlist({ email: form.email.value });
      form.hidden = true;
      document.getElementById("exit-done").hidden = false;
      window.OperatorStack.trackEvent("exit_popup_converted");
    } catch (err) {
      form.querySelector("button[type=submit]").textContent = "Try again";
    }
  });

  document.getElementById("exit-close").addEventListener("click", () => modal.close());
</script>

joinWaitlist returns { success, referral_code, referral_link } and awaits SDK readiness itself, so a fast submit before os.js finishes loading still works. It also credits a stored ?ref= code automatically.

The Mobile Fallback

Touch devices have no cursor, so mouseleave never fires and the popup above silently does nothing on mobile. The closest proxy is weaker.

<script>
  // Fast upward scroll after reading at least 50% of the page
  let lastY = window.scrollY;
  window.addEventListener(
    "scroll",
    () => {
      const y = window.scrollY;
      const depth = (y + innerHeight) / document.documentElement.scrollHeight;
      if (lastY - y > 80 && depth > 0.5) showExit("scroll_up");
      lastY = y;
    },
    { passive: true },
  );
</script>

A fast upward flick after reading half the page is the closest touch equivalent to reaching for the tab bar.

Measure Whether It Earns Its Place

You now log exit_popup_shown and exit_popup_converted. Divide converted by shown for the popup's rate, then check that total signups rose rather than just shifting from the hero form. To test it cleanly, follow the split pattern in How to A/B Test Your Waitlist Page and show the popup to half of sessions. A popup that converts 3 percent of exits but lowers hero signups is not adding anything.