PopStateEvent

PopStateEvent is an event handler for the popstate event on the window.

A popstate event is dispatched to the window every time the active history entry changes between two history entries for the same document. If the history entry being activated was created by a call to history.pushState() or was affected by a call to history.replaceState(), the popstate event's state property contains a copy of the history entry's state object.

Syntax

window.onpopstate = funcRef;

• funcRef is a handler function.

The popstate event

As an example, a page at http://example.com/example.html running the following code will generate alerts as indicated:

window.onpopstate = function(event) {
  alert("location: " + document.location + ", state: " + JSON.stringify(event.state));
};

history.pushState({page: 1}, "title 1", "?page=1");
history.pushState({page: 2}, "title 2", "?page=2");
history.replaceState({page: 3}, "title 3", "?page=3");
history.back(); // alerts "location: http://example.com/example.html?page=1, state: {"page":1}"
history.back(); // alerts "location: http://example.com/example.html, state: null
history.go(2);  // alerts "location: http://example.com/example.html?page=3, state: {"page":3}

Note that even though the original history entry (for http://example.com/example.html) has no state object associated with it, a popstate event is still fired when we activate that entry after the second call to history.back().

Specifications

Browser compatibility

See also

• Manipulating the browser history
• Ajax navigation example