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onreadystatechange event

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

Sets or retrieves the event handler for asynchronous requests.

Syntax

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

Standards information

There are no standards that apply here.

Event information

Synchronous	No
Bubbles	No
Cancelable	No

Event handler parameters

This method has no parameters.

Remarks

The onreadystatechange event was introduced in Windows Internet Explorer 7.

To invoke this event, do one of the following:

Event handlers are called as needed after a request is sent.

Examples

The following script demonstrates how to set an asynchronous event handler that alerts the user when the readyState property of the request reaches complete (4). Note that you must set the event handler after calling open, which resets all properties of the XMLHttpRequest object to their initial value.

Copy


function reportStatus()
{
    if (oReq.readyState == 4 /* complete */) {
        if (oReq.status == 200 || oReq.status == 304) {
            alert('Transfer complete.');
        }
        else {
            // error occurred
        }
    }
}
var oReq = new XMLHttpRequest();
oReq.open("GET", "http://localhost/test.xml", true);
oReq.onreadystatechange = reportStatus;
oReq.send();