How to use basic php dom?

如何操作 PHP dom?

• the CRUD of php node

A. Create

A-1. create node

• create a node
  • $element = $dom->createElement('div', 'text');
• attach $element as a child of $parent (把新增的 $element 加到 $parent 底下)
  • $parent->appendChild($element);

https://www.php.net/manual/en/domdocument.createelement.php

A-2. copy a node

• $dom->cloneNode($deep = false)
  • $deep defaulted false
• copy first child of nodes (僅複製第一層的子節點)
  • $element = $dom->cloneNode();
  • $element = $dom->cloneNode(false);
• copy all descendant nodes (複製所有的子節點)
  • $element = $dom->cloneNode(true);
• The reference of a node will be moved after cloning it.
  • 注意，在 cloneNode 之後，就沒辦法使用 $element-> parentNode() 找到它的父層

https://www.php.net/manual/en/domnode.clonenode.php

B. Read

B-1. get nodes with the specified tag name (找到有某個 tag name 的 node)

$div = $dom->getElementsByTagName('div');

B-2. about attribute

• DOMElement::hasAttribute()
  • Checks to see if attribute exists
• DOMElement::setAttribute()
  • Adds new attribute
• DOMElement::removeAttribute()
  • Removes attribute
• example
  • $searchNode->getAttribute('ID');

https://www.php.net/manual/en/domelement.getattribute.php

C. Update

C-1. replace current node

• $href->parentNode->removeChild($href);
  • https://stackoverflow.com/questions/3602207/php-cant-remove-node-from-domdocument
• $node->parentNode->parentNode->removeChild($node->parentNode);
  • https://stackoverflow.com/questions/48288146/remove-parent-node-in-php

D. Delete

D-1. remove a node

• from end to start (記得從最後一個往前)
  • the order will changed while replacing (因為置換之後，會改變編號)

    $elements = $completePage->getElementsByTagName('a');
    for ($i = $elements->length; --$i >= 0; ) {
      $href = $elements->item($i);
      $href->parentNode->removeChild($href);
    }

• https://stackoverflow.com/questions/15272726/how-to-delete-element-with-domdocument