DOMAttr::isId

Checks if attribute is a defined ID

&reftitle.description; public `bool` `DOMAttr::isId`

This function checks if the attribute is a defined ID.

According to the DOM standard this requires a DTD which defines the attribute ID to be of type ID. You need to validate your document with domdocument.validate or `DOMDocument::$validateOnParse` before using this function.

&reftitle.parameters; &no.function.parameters;
&reftitle.returnvalues;

&return.success;

&reftitle.examples;

### DOMAttr::isId() Example

    <?php

    $doc = new DomDocument;

    // We need to validate our document before referring to the id
    $doc->validateOnParse = true;
    $doc->Load('book.xml');

    // We retrieve the attribute named id of the chapter element
    $attr = $doc->getElementsByTagName('chapter')->item(0)->getAttributeNode('id');

    var_dump($attr->isId()); // bool(true)

    ?>