<div>
  ...Some code here...
</div>

<?php
/**
 * Ok, glad you are here
 * first we get a config instance, and set the settings
 * $config = HTMLPurifier_Config::createDefault();
 * $config->set('Core.Encoding', $this->config->get('purifier.encoding'));
 * $config->set('Cache.SerializerPath', $this->config->get('purifier.cachePath'));
 * if ( ! $this->config->get('purifier.finalize')) {
 *     $config->autoFinalize = false;
 * }
 * $config->loadArray($this->getConfig());
 *
 * You must NOT delete the default settings
 * anything in settings should be compacted with params that needed to instance HTMLPurifier_Config.
 *
 * @link http://htmlpurifier.org/live/configdoc/plain.html
 */

return [
    'encoding'      => 'UTF-8',
    'finalize'      => true,
    'cachePath'     => storage_path('app/purifier'),
    'cacheFileMode' => 0755,
    'settings'      => [
        'default' => [
            'HTML.Doctype'             => 'HTML 4.01 Transitional',
            'HTML.Allowed'             => 'blockquote,h1,h2,h3,h4,h5,h6,pre,code,div[class],b,strong,i,em,a[href|title],ul,ol,li,p[style],br,span[style],img[width|height|alt|src]',
            'CSS.AllowedProperties'    => 'font,font-size,font-weight,font-style,font-family,text-decoration,padding-left,color,background-color,text-align',
            'AutoFormat.AutoParagraph' => false,
            'AutoFormat.RemoveEmpty'   => true,
        ],
        'test'    => [
            'Attr.EnableID' => true
        ],
        "youtube" => [
            "HTML.SafeIframe"      => 'true',
            "URI.SafeIframeRegexp" => "%^(http://|https://|//)(www.youtube.com/embed/|player.vimeo.com/video/)%",
        ],
    ],

];

public function store(Request $request)
    {
        //Validate the data
        $this->validate($request, array(
            'title' => 'required|max:255',
            'slug' => 'required|alpha_dash|min:5|max:255|unique:posts,slug',
            'category_id' =>'required|integer',
            'body' => 'required'
        ));
        //Store in the database
        $post = new Post;

        $post->title = $request->title;
        $post->slug = $request->slug;
        $post->category_id = $request->category_id;
        $post->body = Purifier::clean($request->body, "youtube");

        $post->save();

        $post->tags()->sync($request->tags, false);

        Session::flash('success', 'AWESOMESAUCE! Your post was saved successfully!');

        //redirect to another page
        return redirect()->route('posts.show', $post->id);

    }

<?php
$str = "This is some <b>bold</b> text.";
echo htmlspecialchars($str);
?>

This is some <b>bold</b> text.

pre[class],code

$post->body = clean($request->body, "youtube");