Add attribute to link tag that's generated through wp_register_style?

Question

My original question was answered here: Google Fonts giving: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Is there a way to add the data-noprefix attribute to my Google Fonts link tag?

My functions.php looks like this:

wp_register_script( 'prefixfree', get_template_directory_uri().'/js/prefixfree.min.js', array( 'jquery' ) );
wp_enqueue_script( 'prefixfree' );

wp_register_style( 'google-fonts', 'http://fonts.googleapis.com/css?family=Source+Sans+Pro:300,300italic,400,400italic,600,600italic,700,700italic', '', '', 'all' );
wp_enqueue_style( 'google-fonts' );

Answer 1

This worked for me:

add_filter( 'style_loader_tag', 'add_noprefix_attribute', 10, 2 );

function add_noprefix_attribute($link, $handle) {
    if( $handle === 'google-fonts' ) {
        $link = str_replace( '/>', 'data-noprefix />', $link );
    }
    return $link;
}

Answer 2

style_loader_tag is an official WordPress API, see the documentation: https://developer.wordpress.org/reference/hooks/style_loader_tag/

apply_filters( 'style_loader_tag', $html, $handle, $href, $media )
Filters the HTML link tag of an enqueued style.

First, enqueue your stylesheets
For more information see the documentation: https://developer.wordpress.org/reference/functions/wp_enqueue_style/

function add_styles() {
    // Example loading external stylesheet, could be used in both a theme and/or plugin
    wp_enqueue_style( 'font-awesome-5', 'https://use.fontawesome.com/releases/v5.5.0/css/all.css', array(), null );

    // Example theme
    wp_enqueue_style( 'font-awesome-5', get_theme_file_uri( '/assets/css/fontawesome.min.css' ), array(), null );

    // Example plugin
    wp_enqueue_style( 'font-awesome-5', plugins_url( '/assets/css/fontawesome.min.css', __FILE__ ), array(), null );
};
add_action( 'wp_enqueue_scripts', 'add_styles' );

The $handle is 'font-awesome-5'
I do null so that there is no version number. This way it will be cached.

Simple string replace
A simple str_replace is enough to achieve what you want, see example below

function add_font_awesome_5_cdn_attributes( $html, $handle ) {
    if ( 'font-awesome-5' === $handle ) {
        return str_replace( "media='all'", "media='all' integrity='sha384-B4dIYHKNBt8Bc12p+WXckhzcICo0wtJAoU8YZTY5qE0Id1GSseTk6S+L3BlXeVIU' crossorigin='anonymous'", $html );
    }
    return $html;
}
add_filter( 'style_loader_tag', 'add_font_awesome_5_cdn_attributes', 10, 2 );

Add different atributes
Below an example to add different atributes to (multiple) different stylesheets

function add_style_attributes( $html, $handle ) {

    if ( 'font-awesome-5' === $handle ) {
        return str_replace( "media='all'", "media='all' integrity='sha384-B4dIYHKNBt8Bc12p+WXckhzcICo0wtJAoU8YZTY5qE0Id1GSseTk6S+L3BlXeVIU' crossorigin='anonymous'", $html );
    }

    if ( 'another-style' === $handle ) {
        return str_replace( "media='all'", "media='all' integrity='blajbsf' example", $html );
    }

    if ( 'bootstrap-css' === $handle ) {
        return str_replace( "media='all'", "media='all' integrity='something-different' crossorigin='anonymous'", $html );
    }

    return $html;
}
add_filter( 'style_loader_tag', 'add_style_attributes', 10, 2 );

Add attributes to all styles
Below an example to add the same atributes to more than one stylesheet

function add_attributes_to_all_styles( $html, $handle ) {

        // add style handles to the array below
        $styles = array(
            'font-awesome-5',
            'another-style',
            'bootstrap-css'
        );

        foreach ( $styles as $style ) {
            if ( $style === $handle ) {
                return str_replace( "media='all'", "media='all' integrity='sha384-B4dIYHKNBt8Bc12p+WXckhzcICo0wtJAoU8YZTY5qE0Id1GSseTk6S+L3BlXeVIU' crossorigin='anonymous'", $html );
            }
        }

        return $html;
}
add_filter( 'style_loader_tag', 'add_attributes_to_all_styles', 10, 2 );

script_loader_tag
I also would like to explain the script_loader_tag, because this is also handy, but this API works in combination with wp_enqueue_script.

The script_loader_tag API is almost the same, only some small differences, see documentation: https://developer.wordpress.org/reference/hooks/script_loader_tag/

apply_filters( 'script_loader_tag', $tag, $handle, $src )
Filters the HTML script tag of an enqueued script.

Below an example to defer a single script

function add_defer_jquery( $tag, $handle ) {
    if ( 'jquery' === $handle ) {
        return str_replace( "src", "defer src", $tag );
    }
    return $tag;
}
add_filter( 'style_loader_tag', 'add_defer_jquery', 10, 2 );

Below an example to defer more than one script

function add_defer_attribute( $tag, $handle ) {

    // add script handles to the array below
    $scripts_to_defer = array(
        'jquery',
        'jquery-migrate',
        'bootstrap-bundle-js'
    );

    foreach ( $scripts_to_defer as $defer_script ) {
        if ( $defer_script === $handle ) {
            return str_replace( "src", "defer src", $tag );
        }
    }

    return $tag;
}
add_filter( 'script_loader_tag', 'add_defer_attribute', 10, 2 );

So I have explained both API's style_loader_tag and script_loader_tag. And I gave some examples for both API's I hope that this is useful for a lot of people out there. I have experience with both API's.