Add custom class to WordPress iframe video, youtube and vimeo iframe.
WordPress Iframe Video Filter
Using embed_oembed_html filter we will add custom class to wordpress iframe video, youtube and vimeo.
Usage Filter
Copy function code and paste it in your functions.php file.
function custom_class_to_wordpress_iframe_video( $html ) {
if( preg_match('/(youtube.com)/', $html) ){ // if youtube video
return str_replace('<iframe', '<iframe class="my-youtube-video"', $html); // add my custom class "my-youtube-video"
}
elseif( preg_match('/(vimeo.com)/', $html) ){ // if vimeo video
return str_replace('<iframe', '<iframe class="my-vimeo-video"', $html); // add my custom class "my-vimeo-video"
}
else{
return $html;
}
}
add_filter('embed_oembed_html', 'custom_class_to_wordpress_iframe_video', 99, 4);
Note: this is “my-youtube-video” youtube iframe class, change it to your custom class, and this is “my-vimeo-video” vimeo iframe class, change it to your custom class.
Do you want to add class to links? Use Extend Link Plugin, All-In-One.

It’s very useful for me and thanks for the code.