Creates an element with the specified namespace URI and qualified name.

To create an element without specifying a namespace URI, use the createElement() method.

namespaceURI

A string that specifies the namespace URI to associate with the element. The namespaceURI property of the created element is initialized with the value of namespaceURI. See Valid Namespace URIs.

qualifiedName

A string that specifies the type of element to be created. The nodeName property of the created element is initialized with the value of qualifiedName.

options Optional

An optional ElementCreationOptions object containing a single property named is, whose value is the tag name for a custom element previously defined using customElements.define(). For backwards compatibility with previous versions of the Custom Elements specification, some browsers will allow you to pass a string here instead of an object, where the string's value is the custom element's tag name. See Extending native HTML elements for more information on how to use this parameter.

The new element will be given an is attribute whose value is the custom element's tag name. Custom elements are an experimental feature only available in some browsers.

The new Element.

NamespaceError DOMException

Thrown if the namespaceURI value is not a valid namespace URI.

InvalidCharacterError DOMException

Thrown if the qualifiedName value is not a valid XML name; for example, it starts with a number, hyphen, or period, or contains characters other than alphanumeric characters, underscores, hyphens, or periods.

HTML

http://www.w3.org/1999/xhtml

SVG

http://www.w3.org/2000/svg

MathML

http://www.w3.org/1998/Math/MathML

This creates a new <div> element in the XHTML namespace and appends it to the vbox element. Although this is not an extremely useful XUL document, it does demonstrate the use of elements from two different namespaces within a single document:

<?xml version="1.0"?>
<page xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
      xmlns:html="http://www.w3.org/1999/xhtml"
      title="||Working with elements||"
      onload="init()">

<script type="application/javascript"><![CDATA[
 let container;
 let newdiv;
 let txtnode;

 function init(){
   container = document.getElementById("ContainerBox");
   newdiv = document.createElementNS("http://www.w3.org/1999/xhtml", "div");
   txtnode = document.createTextNode("This is text that was constructed dynamically with createElementNS and createTextNode then inserted into the document using appendChild.");
   newdiv.appendChild(txtnode);
   container.appendChild(newdiv);
 }

]]></script>

 <vbox id="ContainerBox" flex="1">
  <html:div>
   The script on this page will add dynamic content below:
  </html:div>
 </vbox>

</page>

• document.createElement()
• document.createTextNode()
• Element.namespaceURI
• Namespaces in XML