WindowEventHandlers.onpopstate
The onpopstate
property of the
WindowEventHandlers
mixin is the event handler for
processing popstate
events on the window.
A popstate
event is dispatched to the window each time the active history
entry changes between two history entries for the same document. If the activated
history entry 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.
Note: Calling history.pushState()
or
history.replaceState()
won't trigger a popstate
event. The
popstate
event is only triggered by performing a browser action, such as
clicking on the back button (or calling history.back()
in JavaScript),
when navigating between two history entries for the same document.
Syntax
window.onpopstate = funcRef;
funcRef
is a handler function.
Examples
For 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
Specification |
---|
HTML Standard # handler-window-onpopstate |
Browser compatibility
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