WordPress plugin for highlight.js

t5-highlight.php

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: T5 Highlight
 * Description: Use highlight.js on front end. Mark code with <code>&lt;pre class="language-php"&gt;&lt;code&gt;your code&lt;/code&gt;&lt;/pre&gt;</code>
 * Version:     31.10.14
 * Required:    4.0
 * Author:      Thomas Scholz
 * Author URI:  http://toscho.de
 * License:     MIT
 * License URI: http://www.opensource.org/licenses/mit-license.php
 */
namespace T5\Frontend\Highlight;

/**
 * Class Highlight
 *
 * @version 2014.10.31
 * @author  toscho
 */
class Highlight
{
	/**
	 * @type string
	 */
	private $highlight_url;

	/**
	 * @param string $plugin_file Path to main file
	 */
	public function __construct( $plugin_file )
	{
		$this->highlight_url = plugin_dir_url( $plugin_file ) . 'h/';
	}

	/**
	 * @wp-hook wp_loaded
	 * @return void
	 */
	public function setup()
	{
		$this->register();
		add_action( 'wp_enqueue_scripts',      array( $this, 'enqueue' ) );
		add_action( 'wp_print_footer_scripts', array( $this, 'initialize' ), 11 );
	}

	/**
	 * Registers script and stylesheet
	 *
	 * @wp-hook wp_loaded
	 * @return  void
	 */
	public function register()
	{
		$js_url = $this->highlight_url . 'highlight.pack.js';
		wp_register_script( 'highlight', $js_url, array(), FALSE, TRUE );

		$css_url = $this->highlight_url . 'styles/hybrid.css';
		wp_register_style( 'highlight', $css_url );
	}

	/**
	 * Enqueues script and stylesheet
	 *
	 * @wp-hook wp_enqueue_scripts
	 * @return  void
	 */
	public function enqueue()
	{
		wp_enqueue_script( 'highlight' );
		wp_enqueue_style( 'highlight' );
	}

	/**
	 * Initializes the script
	 *
	 * @wp-hook wp_print_footer_scripts
	 * @return  void
	 */
	public function initialize()
	{
		?><script>hljs.initHighlightingOnLoad();</script><?php
	}
}

is_admin() || add_action( 'wp_loaded', array( new Highlight( __FILE__ ), 'setup' ) );

This doesn't work out of the box, you need to add some steps:

1. Put this file into a directory.
2. Go to https://highlightjs.org/download/ and create a custom package with languages you need. The smaller the better.
3. Put the downloaded package into a subdirectory named h/.
4. Upload the plugin directory to you WordPress plugin directory, and enable it per backend.

That's it.

Note directory h not h/

Worked like a charm.