1- First you have to make a child theme of your current theme.
2- Then, in your child theme create a functions.php file
3- Create a js folder and put fitty.min.js inside it and create a child.js file also inside this js folder
4- In functions.php of your child theme add the following :
<?php // Opening PHP tag - nothing should be before this, not even whitespace
function child_scripts() {
wp_enqueue_script( 'fitty', get_theme_file_uri( '/js/fitty.min.js' ), array(), filemtime( get_theme_file_path( '/js/fitty.min.js' ) ), true );
wp_enqueue_script( 'child', get_theme_file_uri( '/js/child.js' ), array( 'jquery' ), filemtime( get_theme_file_path( '/js/child.js' ) ), true );
}
add_action( 'wp_enqueue_scripts', 'child_scripts' );
5- In child.js add the following :
(function ($) {
fitty('#my-element'); // Here fitty is targeting the element with an id='my-element'
})(jQuery);
Hope this will help you 🙂