PHP - Manual: DOMNodeList

2025-10-31

DOMNodeList::count »

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The DOMNodeList class

(PHP 5, PHP 7, PHP 8)

简介

Represents a live list of nodes.

类摘要

class DOMNodeList implements IteratorAggregate, Countable {

/* 属性 */

public readonly int $length;

/* 方法 */

public count(): int

public getIterator(): Iterator

public item(int $index): DOMElement|DOMNode|DOMNameSpaceNode|null

}

属性

length: The number of nodes in the list. The range of valid child node indices is 0 to length - 1 inclusive.

更新日志

版本	说明
8.0.0	DOMNodeList implements IteratorAggregate now. Previously, Traversable was implemented instead.
7.2.0	The Countable interface is implemented and returns the value of the length property.

注释

注意: Nodes in the list can be accessed by array syntax.

参见

» W3C specification of NodeList

If you want to recurse over a DOM then this might help: 
<?php 

/**
 * PHP's DOM classes are recursive but don't provide an implementation of 
 * RecursiveIterator. This class provides a RecursiveIterator for looping over DOMNodeList
 */
class DOMNodeRecursiveIterator extends ArrayIterator implements RecursiveIterator {

  public function __construct (DOMNodeList $node_list) {

$nodes = array();
    foreach($node_list as $node) {
$nodes[] = $node;
    }

parent::__construct($nodes);

  }

  public function getRecursiveIterator(){
    return new RecursiveIteratorIterator($this, RecursiveIteratorIterator::SELF_FIRST);
  }

  public function hasChildren () {
    return $this->current()->hasChildNodes();
  }


  public function getChildren () {
    return new self($this->current()->childNodes);
  }

}
?>

down

geompse at gmail dot com ¶

14 years ago

Note that $length is calculated (php5.3.2).
Iterating over a large NodeList may be time expensive.

Prefer :
$nb = $nodelist->length;
for($pos=0; $pos<$nb; $pos++)

Than:
for($pos=0; $pos<$nodelist->length; $pos++)

I had a hard time figuring that out...

down

brack at wjp dot de ¶

16 years ago

In PHP 5.2.5 (Windows) it is not possible to iterate correctly over the DOMNodeList object returned by DOMNode->childNodes using foreach. Instead I had to use the for loop in conjunction with the item() method of DOMNodeList for iterating over all child nodes correctly.

I don't know whether this is really a bug, but apparently it is.

down

c dot 1 at smithies dot org ¶

16 years ago

You can modify, and even delete, nodes from a DOMNodeList if you iterate backwards:

$els = $document->getElementsByTagName('input');
for ($i = $els->length; --$i >= 0; ) {
  $el = $els->item($i);
  switch ($el->getAttribute('name')) {
    case 'MAX_FILE_SIZE' :
      $el->parentNode->removeChild($el);
    break;
    case 'inputfile' :
      $el->setAttribute('type', 'text');
    //break;
  }
}

down

drichter at muvicom dot de ¶

16 years ago

I have done some testing and have found 2 results:
(My System: Win XP with PHP 5.2.1)

1) Iteration with foreach does function correctly as "james dot j dot hackett at gmail dot com" writes, _if_ you only do readonly stuff with foreach or minor writings of some attributes.

2) foreach does not function, if you are doing some DOM-Operations while iterating. In my situation it was adding the iterated $node as an child to an new node:

$newNode = $dom->createElement('newNode') ;
foreach ($nodeList as $node) {
  echo $node->nodeValue ;
  $newNode->appendChild($node) ;
}

This only gives you the first element ...

I'm interpreting it as an confusing but correct behavior because of the changes within the $dom-object while appending the node at an additional place ... 

So, if you want to do something like 2) use for, length and item() :)

down

niko at yopmail dot com ¶

3 years ago

It's worth to mention that DOMNodeList is not an Array,  so you have to convert first to an array before to use for, foreach or array_map, array_filter, array_walk functions.

Use iterator_to_array to make the conversion ( since PHP 5.1.0 ) .

<code>
  /* @ suppress warning var_dump not yet implemented for class */

@array_walk( iterator_to_array( $Some_NodeList ), 'var_dump' ) );

foreach( iterator_to_array( $Some_NodeList ) as $node )
    @var_dump( $node );

</code>

Hope is usefull.

down

james dot j dot hackett at gmail dot com ¶

16 years ago

In Response to 'kassah at gmail'

You don't need to convert a DOMNodeList to an array in order iterate through it using 'foreach'.  You can use foreach directly with the DOMNodeList.

$nodeList = $someDomDocument->getElementsbytagname('user');

foreach ($nodeList as $node) {
    echo $node->nodeValue;
}

down

bobvandell at hotmail dot com ¶

16 years ago

That's actually incorrect. You can use function results as objects. It makes building an API for your database very clean and neat. For example:

Our code:

$articles = Node::screate('tags', 123456)->assets('like:title:test')->articles;

We use the above code to get articles that are linked to assets that are linked to a specific tag in our database.

down

-2

drichter at muvicom dot de ¶

16 years ago

Addition to my first note:

An traditional for-loop does not allow you to change the DOM-tree while looping - the effects are the nearly the same as with foreach. So you have to collect the nodes in an array and do the tree-altering stuff within a second loop (looping the array this time ...)

＋添加备注

官方地址：https://www.php.net/manual/en/class.domnodelist.php

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PHP官方手册 - 互联网笔记

The DOMNodeList class

简介

类摘要

属性

更新日志

注释

参见

目录

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