jQuery .unload() Method

What Is .unload()?

.unload() was jQuery’s shorthand (since 1.0) for binding or triggering the browser unload event — almost always on window. It is gone in jQuery 3.x. Use .on("unload") / .trigger("unload"), or prefer pagehide for modern cleanup.

// Removed in jQuery 3.0 — only works in 1.x / 2.x
$(window).unload(function () {
  // page is leaving
});

$(window).unload(); // trigger

// Modern replacements
$(window).on("unload", handler);
$(window).trigger("unload");

// Often better for cleanup today
$(window).on("pagehide", handler);

How to Use .unload()

Recognize legacy calls, bind on window, and migrate to .on() / .trigger().

1. In old code, bind with $(window).unload(handler) (jQuery 1.x / 2.x only).
2. Optionally pass eventData: .unload(data, handler) → .on("unload", data, handler).
3. Trigger with no-arg .unload() (legacy) or .trigger("unload") (preferred).
4. Keep handlers light — browsers ignore alert() / confirm() inside unload.
5. For new apps, prefer pagehide or visibilitychange over unload.

Pseudocode

legacy (jQuery 1.x / 2.x only):
  call $(window).unload(handler)
      → internally: $(window).on("unload", handler)

  call $(window).unload()
      → internally: $(window).trigger("unload")

when user leaves the page:
  fire unload on window
      for each registered handler:
          call handler(event)
          // cannot cancel with preventDefault()

to migrate:
  .unload(fn)       → .on("unload", fn)
  .unload(data, fn) → .on("unload", data, fn)
  .unload()         → .trigger("unload")

prefer today:
  .on("pagehide", fn) for cleanup

Cheat Sheet

Quick map from the removed shorthand to modern APIs.

Live Preview

This site loads jQuery 3.x, so .unload() is missing. The demo uses the modern .on("unload") / .trigger("unload") replacement.

Ready — pick an action and click Run.

jQuery Examples

Examples 1–3 use jQuery 2.2.4 so .unload() exists. Examples 4–5 show jQuery 3.x migration.

$(window).unload(function () {
  $("#log").text("Unload handler ran");
});

// Demo only — real unload fires on navigation
$(window).trigger("unload");

Unload handler ran
(jQuery 2.2.4 lab — method missing in 3.x)

$(window).unload({ appId: "dashboard" }, function (event) {
  $("#log").text("Cleaning up: " + event.data.appId);
});

$(window).trigger("unload");

Cleaning up: dashboard

$(window).unload(function () {
  $("#log").text("Handler ran via .unload()");
});

$("#fire").on("click", function () {
  $(window).unload(); // legacy trigger
});

Click fire → Handler ran via .unload()
No real page navigation required

function cleanup() {
  localStorage.setItem("draftSaved", "true");
  $("#log").text("cleanup ran — draftSaved=true");
}

$(window).on("unload", cleanup);
$(window).trigger("unload");
$(window).off("unload", cleanup);

Bound → triggered → removed
Works on jQuery 3.7 (no .unload method)

$(window).on("pagehide", function (event) {
  var persisted = event.originalEvent && event.originalEvent.persisted;
  $("#log").text(
    persisted ? "pagehide — page cached (bfcache)" : "pagehide — page leaving"
  );
});

pagehide — page leaving
(or cached, when the browser uses bfcache)

Performance Notes

Keep leave-time work tiny. Prefer navigator.sendBeacon or async patterns started earlier — do not rely on long unload handlers.

Key Takeaways