DOM
PHP Manual

DOMDocument->getElementById()

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DOMDocument->getElementById() — Searches for an element with a certain id

说明

DOMDocument
DOMElement getElementById ( string $elementId )

This function is similar to DOMDocument->getElementsByTagName() but searches for an element with a given id.

For this function to work, you will need either to set some ID attributes with DOMElement->setIdAttribute() or a DTD which defines an attribute to be of type ID. In the later case, you will need to validate your document with DOMDocument->validate() or DOMDocument->validateOnParse before using this function.

参数

elementId

The unique id value for an element.

返回值

Returns the DOMElement or NULL if the element is not found.

范例

Example#1 DOMDocument->getElementById() Example

<?php

$doc 
= new DomDocument;

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

echo 
"The element whose id is books is: " $doc->getElementById('books')->tagName "\n";

?>

上例将输出:

The element whose id is books is: chapter

参见


DOM
PHP Manual