---
title: onreadystatechange
framework: tvmljs
role: symbol
role_heading: Instance Property
path: tvmljs/xmlhttprequest/1627414-onreadystatechange
---

# onreadystatechange

A callback function that is called when the readyState attribute changes.

## Declaration

```data
attribute function onreadystatechange;
```

```data
attribute EventHandler onreadystatechange;
```

## Discussion

Discussion Do not use this attribute in conjunction with synchronous requests. This attribute must be set to a function; for example, XMLHttpRequest.onreadystatechange = function () {}.

## See Also

### Implementing Callback Functions

- [onabort](tvmljs/xmlhttprequest/1627410-onabort.md)
- [onerror](tvmljs/xmlhttprequest/1627328-onerror.md)
- [onload](tvmljs/xmlhttprequest/1627316-onload.md)
- [onloadend](tvmljs/xmlhttprequest/1627365-onloadend.md)
- [onloadstart](tvmljs/xmlhttprequest/1627440-onloadstart.md)
- [ontimeout](tvmljs/xmlhttprequest/1627321-ontimeout.md)