Shortcode: Create Headings with anchor + link icon

heading-shortcode.php

<?php // only copy this line if needed!

// REQUIRES PHP 5.3+

/**
 * Create a shortcode to insert a header with an anchor icon.
 * Use [heading size="2" id="anchor"]Heading[/heading]
 *
 * Recommended: Add prefix / change shortcode name to avoid conflicts
*/

function br_heading_shortcode( $atts, $content = null ) {

	// set default size="2" to default to h2
	$a = shortcode_atts( array(
		'size' => '2',
		'id' => false,
	), $atts );

	// generate an ID if we don't have one passed in
	$anchor = $a['id'] ?: sanitize_title( $content );

	// optional: ensure Dashicons is enqueued
	wp_enqueue_script( 'dashicons' );

	ob_start();
	
	// replace <span class="dashicons dashicons-admin-links"></span> with a different icon if desired
	?>
	<h<?php echo esc_attr( $a['size'] ); ?> id="<?php echo esc_attr( $anchor ); ?>">
		<a href="#<?php echo esc_attr( $anchor ); ?>">
			<span class="dashicons dashicons-admin-links"></span>
		</a> 
		<?php echo wp_kses_post( $content ); ?>
	</h<?php echo esc_attr( $a['size'] ); ?>>

	<?php
	return ob_get_clean();
}
add_shortcode( 'heading', 'br_heading_shortcode' );