Manipulate Wordpress Output Buffer with `DOMXPath`and `DOMDocument`.md

#wordpress #xquery #domdocument

theme-child/function.php

<?php
function callback($buffer) {
	
	// prevent ajax/json and admin stuff being mangled
	if (strpos(trim($buffer), '<') !== 0 || is_admin()) {
		return $buffer;
	}
  
  	// in case we have some mangled special chars in the output,
	// use this. <https://davidwalsh.name/domdocument-utf8-problem>
	$html = mb_convert_encoding($buffer, 'HTML-ENTITIES', 'UTF-8');
	
	$dom = new DOMDocument();
	$dom->recover = true;
	//$dom->substituteEntities = true;
	$dom->formatOutput = true;
	$dom->preserveWhiteSpace = true;
	
	// set error level
	// uncomment to suspress warnings that happen with embedded SVG, duplicate ids
	// and raw entities like & instead of &amp;
	//$internalErrors = libxml_use_internal_errors(true);
	
	// load HTML 
	// LIBXML_HTML_NODEFDTD 
	// keeps linebreaks after <script> tags being rearranged
	// http://stackoverflow.com/a/32028596/814031
	// http://stackoverflow.com/a/29499398/814031
	$dom->loadHTML($html, LIBXML_HTML_NODEFDTD);
	
	// collect the suspressed warnings/errors and print them out
	//$errors = libxml_get_errors();
	//var_dump($errors);
	
	// Restore error level
	//libxml_use_internal_errors($internalErrors);

	$xpath = new DOMXPath($dom); 
	
	$featuredImage = $xpath->query('//*[@id="main"]//div[contains(@class, "kadence-thumbnail-position-above")]')->item(0);
	$heroContainer = $xpath->query('//div[contains(@class, "entry-hero-container-inner")]')->item(0);
	$heroContainer->appendChild($featuredImage->cloneNode(true));
	$featuredImage->parentNode->removeChild($featuredImage);
	
	return $dom->saveHTML();

}

function buffer_start() { ob_start("callback"); }

function buffer_end() { ob_end_flush(); }

add_action('wp_loaded', 'buffer_start');
add_action('shutdown', 'buffer_end');

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