The DOMNode::insertBefore() function is an inbuilt function in PHP which is used to insert a new node before a certain another node.
Syntax:
DOMNode DOMNode::insertBefore( DOMNode $newNode, DOMNode $refNode )
Parameters:This function accepts two parameters as mentioned above and described below:
- $newNode: It specifies the new node.
- $refNode (Optional): It specifies the reference node. If not supplied, newnode is appended to the children.
Return Value: This function returns the inserted node.
Exceptions: This function throws DOM_NO_MODIFICATION_ALLOWED_ERR, if this node is readonly or if the previous parent of the node being inserted is readonly. DOM_HIERARCHY_REQUEST_ERR, if this node is of a type that does not allow children of the type of the $newNode node, or if the node to append is one of this node’s ancestors or this node itself, DOM_WRONG_DOCUMENT_ERR, if $newNode was created from a different document than the one that created this node, DOM_NOT_FOUND, if $refNode is not a child of this node.
Below given programs illustrate the DOMNode::insertBefore() function in PHP:
Program 1:
<?php   // Create a new DOMDocument $dom = new DOMDocument();   // Create a paragraph element $p_element = $dom->createElement('p',       'This is the paragraph element!');   // Append the child $dom->appendChild($p_element);   // Create a paragraph element $h_element = $dom->createElement('h1',       'This is the heading element!');   // Insert heading before HTML $dom->insertBefore($h_element, $p_element);   // Render the output echo $dom->saveXML(); ?> |
Output:
<?xml version="1.0"?> <h1>This is the heading element!</h1> <p>This is the paragraph element!</p>
Program 2:
<?php   // Create a new DOMDocument $dom = new DOMDocument();   // Create a paragraph element $p_element = $dom->createElement('p',       'neveropen, paragraph');   // Append the child $dom->appendChild($p_element);   // Create a paragraph element $h_element = $dom->createElement('h1',       'neveropen, heading');   // When second argument is not provided // It will appended to the child $dom->insertBefore($h_element);   // Render the output echo $dom->saveXML(); ?> |
Output:
<?xml version="1.0"?> <p>neveropen, paragraph</p> <h1>neveropen, heading</h1>
Reference: https://www.php.net/manual/en/domnode.insertbefore.php
