Node: lookupPrefix() method
The lookupPrefix()
method of the Node
interface
returns a string containing the prefix for a given namespace URI, if present,
and null
if not.
When multiple prefixes are possible, the first prefix is returned.
Syntax
js
lookupPrefix(namespace)
Parameters
namespace
-
A string containing the namespace to look the prefix up.
Note: This parameter is not optional but can be set to
null
.
Return value
A string containing the corresponding prefix, or null
if none has been found.
If namespace
is null, or the empty string, lookupPrefix()
returns null
.
If the node is a DocumentType
or a DocumentFragment
,
lookupPrefix()
always returns null
.
Example
html
Prefix for <code>http://www.w3.org/2000/svg</code> on <output>:
<output>Not tested</output>.<br />
Prefix for <code>http://www.w3.org/XML/1998/namespace</code> on <output>:
<output>Not tested</output>.<br />
Prefix for <code>http://www.w3.org/TR/html4/</code> on <output>:
<output>Not tested</output>.<br />
Prefix for <code>https://www.w3.org/1999/xlink</code> on <output>:
<output>Not tested</output>.<br />
Prefix for <code>http://www.w3.org/2000/svg</code> on <svg>:
<output>Not tested</output>.<br />
Prefix for <code>https://www.w3.org/1999/xlink</code> on <svg>:
<output>Not tested</output>.<br />
Prefix for <code>http://www.w3.org/XML/1998/namespace</code> on <svg>:
<output>Not tested</output>.<br />
<svg xmlns:t="http://www.w3.org/2000/svg" height="1"></svg>
<button>Click to see the results</button>
js
const button = document.querySelector("button");
button.addEventListener("click", () => {
const aHtmlElt = document.querySelector("output");
const aSvgElt = document.querySelector("svg");
const result = document.getElementsByTagName("output");
result[0].value = aHtmlElt.lookupPrefix("http://www.w3.org/2000/svg"); // true
result[1].value = aHtmlElt.lookupPrefix(
"http://www.w3.org/XML/1998/namespace"
); // false
result[2].value = aHtmlElt.lookupPrefix("http://www.w3.org/TR/html4/"); // true
result[3].value = aHtmlElt.lookupPrefix("https://www.w3.org/1999/xlink"); // false
result[4].value = aSvgElt.lookupPrefix("http://www.w3.org/2000/svg"); // true
result[5].value = aSvgElt.lookupPrefix("https://www.w3.org/1999/xlink"); // true
result[6].value = aSvgElt.lookupPrefix(
"http://www.w3.org/XML/1998/namespace"
); // false
});
Specifications
Specification |
---|
DOM Standard # dom-node-lookupprefix |
Browser compatibility
BCD tables only load in the browser