additional-shortcode.php

<?php

/************************
 * Clean up shortcode
 ***********************/

function jeg_clean_shortcodes($content) {
    $array = array (
        '<p>[' => '[',
        ']</p>' => ']',
        ']<br />' => ']'
    );
    $content = strtr($content, $array);
    return $content;
}

add_filter('the_content', 'jeg_clean_shortcodes');

/* Plugin Name: My TinyMCE Buttons */
add_action( 'admin_init', 'jeg_tinymce_button' );

function jeg_tinymce_button() {
    if ( current_user_can( 'edit_posts' ) && current_user_can( 'edit_pages' ) ) {
        add_filter( 'mce_external_plugins', 'jeg_add_tinymce_button' );
    }
}

function jeg_add_tinymce_button( $plugin_array ) {
    $plugin_array['jcode'] = get_template_directory_uri() . "/assets/tinymce/jcode.js"  ;
    return $plugin_array;
}