---
title: lookupPrefix
framework: WebKit JS
role: symbol
role_heading: Instance Method
platforms: [Safari Desktop 10.0+, Safari Mobile 10.0+]
path: webkitjs/node/1630117-lookupprefix
---

# lookupPrefix

## Declaration

```data
DOMString? lookupPrefix(
    DOMString? namespaceURI
);
```