onreadystatechange event

[This documentation is preliminary and is subject to change.]

Fires when the state of the object has changed.


HTML Attribute <element onreadystatechange = "handler(event)">
Event Property object.onreadystatechange = handler;
attachEvent Method object.attachEvent("onreadystatechange", handler)
addEventListener Method object.addEventListener("readystatechange", handler, useCapture)

Standards information

There are no standards that apply here.

Event information

Synchronous No
Bubbles No
Cancelable No

Event handler parameters


You can use the readyState property to query the current state of the element when the onreadystatechange event fires.

All elements expose an onreadystatechange event. The following objects always fire the event because they load data: applet, document, frame, frameSet, iframe, img, link, object, script, and xml elements. Other objects will only fire the onreadystatechange event when a DHTML Behavior is attached.

When working with behaviors, wait for the onreadystatechange event to fire and verify that the readyState property of the element is set to complete to ensure that the behavior is completely downloaded and applied to the element. Until the onreadystatechange event fires, if you use any of the behavior-defined members before attaching the behavior to the element, a scripting error can result, indicating that the object does not support that particular property or method.

Signals the ready state of the document.

To invoke this event, do one of the following:

  • Change the ready state.

The pEvtObj parameter is required for the following interfaces:

See also




Introduction to Data Binding



Build date: 1/23/2012