Shortcode with attributes

shortcode-with-attributes.php

<?php /*
    Shortcode CTA button for use in the editor.
    Example usage:

    [button href="https://www.google.com.au" target="_blank"]Visit Google[/button]
*/
function button( $atts, $content = null ) {
    $a = shortcode_atts( array(
        'class'     => 'button-link external',
        'href'      =>  '#',
        'target'    => '_self'
    ), $atts );

    return '<a class="' . esc_attr($a['class']) . '" href="' . esc_attr($a['href']) . '" target="' . esc_attr($a['target']) . '" >' . $content . '</a>';
}
add_shortcode( 'button', 'button' );