Element: setAttributeNodeNS() method

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This feature is well established and works across many devices and browser versions. Its been available across browsers since July 2015.

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The setAttributeNodeNS() method of the Element interface adds a new namespaced Attr node to an element.

If you don't need to work with the attribute node (such as cloning from another element) before adding it, you can use the setAttributeNS() method instead.

If you are working with HTML documents and you don't need to specify the requested attribute as being part of a specific namespace, use the setAttribute() method instead.

Syntax

setAttributeNodeNS(attributeNode)

Parameters

attributeNode: The Attr node to add to the element.

Return value

The replaced attribute node, if any, returned by this function.

Examples

// <div id="one" xmlns:myNS="http://www.mozilla.org/ns/specialspace"
//            myNS:special-align="utterleft">one</div>
// <div id="two">two</div>

const myns = "http://www.mozilla.org/ns/specialspace";
const d1 = document.getElementById("one");
const d2 = document.getElementById("two");
const a = d1.getAttributeNodeNS(myns, "special-align");
d2.setAttributeNodeNS(a.cloneNode(true));
alert(d2.attributes[1].value); // returns: `utterleft'

Notes

If the specified attribute already exists on the element, then that attribute is replaced with the new one and the replaced one is returned.

Note that if you try to set without cloning the node, you may see NS_ERROR_DOM_INUSE_ATTRIBUTE_ERR "Attribute already in use" error, as the DOM requires cloning for Attr to be reused (unlike other Nodes which can be moved).