WordPress auto add IDs to headings

wordpress-automatically-add-ids.php

<?php
/**
 * Automatically add IDs to headings such as <h2></h2>
 */
function auto_id_headings( $content ) {

	$content = preg_replace_callback( '/(\<h[1-6](.*?))\>(.*)(<\/h[1-6]>)/i', function( $matches ) {
		if ( ! stripos( $matches[0], 'id=' ) ) :
			$matches[0] = $matches[1] . $matches[2] . ' id="' . sanitize_title( $matches[3] ) . '">' . $matches[3] . $matches[4];
		endif;
		return $matches[0];
	}, $content );

    return $content;

}
add_filter( 'the_content', 'auto_id_headings' );

@JeroenSormani In 2023 where emojis are popular to use in headlines, we need to filter and remove emojis from added to the ID as it breaks the function of anchor link when there is an emoji in the ID.