The itemid
global attribute provides microdata in the form of a unique, global identifier of an item. An itemid
attribute can only be specified for an element that has both itemscope
and itemtype
attributes. Also, itemid
can only be specified on elements that possess an itemscope
attribute whose corresponding itemtype
refers to or defines a vocabulary that supports global identifiers.
The exact meaning of an itemtype
's global identifier is provided by the definition of that identifier within the specified vocabulary. The vocabulary defines whether several items with the same global identifier can coexist and, if so, how items with the same identifier are handled.
Note: The WHATWG definition specifies that an itemid
must be a URL. However, the following example correctly illustrates that a URN may also be used. This inconsistency may reflect the incomplete nature of the Microdata specification.
Example
HTML
<dl itemscope itemtype="http://vocab.example.net/book" itemid="urn:isbn:0-330-34032-8"> <dt>Title <dd itemprop="title">The Reality Dysfunction <dt>Author <dd itemprop="author">Peter F. Hamilton <dt>Publication date <dd><time itemprop="pubdate" datetime="1996-01-26">26 January 1996</time> </dl>
Structured data
itemscope | itemtype: itemid |
http://vocab.example.net/book: urn:isbn:0-330-34032-8
|
|
itemprop | title | The Reality Dysfunction | |
itemprop | author |
Peter F. Hamilton
|
|
itemprop | pubdate | 1996-01-26 |
Result
Specifications
Specification | Status | Comment |
---|---|---|
HTML Living Standard The definition of 'itemid' in that specification. |
Living Standard |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
itemid | Chrome Full support Yes | Edge Full support 12 | Firefox Full support Yes | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support Yes | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support