使用php DOM api删除元标记时出现问题

问题描述：

$html = new DOMDocument();
           $html->loadHTMLFile($filename);

           $meta = $html->getElementsByTagName("meta");


           foreach($meta as $oldmeta_tags)
           {

               $parent = $oldmeta_tags->parentNode;
               $parent->removeChild($oldmeta_tags);

           }
         echo "<br>Number of bytes stored = ".$html->saveHTMLFile($filename);
           $result[] = file_get_contents($filename);

Some of the meta tags are removed and some are not. please help what i am doing wrong

  $ html = new DOMDocument（）; 
 $ html-＆gt; loadHTMLFile（$ filename）;  
 
 $ meta = $ html-＆gt; getElementsByTagName（“meta”）; 
 
 
 foreach（$ meta as $ oldmeta_tags）
 {
 
 $ parent = $ oldmeta_tags-＆gt; parentNode;  
 $ parent-＆gt; removeChild（$ oldmeta_tags）; 
 
} 
 echo“＆lt; br＆gt;存储的字节数=”。$ html-＆gt; saveHTMLFile（$ filename）; 
 $ result []  = file_get_contents（$ filename）; 
  code>  pre> 
 
 删除了一些元标记，而某些元标记则没有删除。 请帮助我做错了 p> 
  div>

答

When you use foreach to iterate over the DOMNodeList and remove an element, you are changing the DOMNodeList content, so nodes will be skipped. You have to iterate backwards:

$nodes = $dom->getElementsByTagName('meta');
for ($i = $nodes->length - 1; $i >= 0; $i--) {
    $nodes->item($i)->parentNode->removeChild($nodes->item($i));
}

答

You're looping over the array and removing from it at the same time.

Unfortunately, this means that every time you remove a child inside the loop, the next loop iteration skips a node. foreach is not "clever enough" in conjunction with DOMDocument to do this intelligently.

Instead of foreach, use indexes:

$meta = $html->getElementsByTagName("meta");
for ($i = $meta->length - 1; $i >= 0; $i--) { // `foreach` breaks the `removeChild`
   $child = $meta->item($i);
   $child->parentNode->removeChild($child);
}

使用php DOM api删除元标记时出现问题

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