在子主题中包含用于表单验证的Jquery文件

I've created a child theme and am running my site on that so that I can customise a form that I'm including on certain pages using the plugin 'contact-form-7". In my child folder I've placed a style.css, functions.php and js/custom_script.js. the style sheet is being imported fine but I can't seem to get my validation jquery file working on that form. This is the code I've been using:

add_action( 'wp_enqueue_scripts', 'add_my_script' );
function add_my_script() {
wp_register_script( 'custom_script', get_stylesheet_directory_uri() .               '/js/custom_script.js' ,array( 'jquery'));

    wp_enqueue_script( 'custom_script' );
}

console isn't logging any errors but I can't seem to find it in the web tools side bar UNLESS I remove "js/" when the custom_script is called, in which case a GET error pops up.

I'm guessing I'm incorrectly importing the file and honestly I can't quite get my head around these hooks and importing files just yet- only been using wordpress a short time.

Any help much appreciated.

I believe that you haven't included the JQuery file? You have to download it first https://jquery.com/download/, and then register it as you did with "custom_script", you just have to put it before the "custom_script" in functions.php, inside "custom_script.js" you could also do:

$(document).ready(function(){

});

Go to your console and if you see:

Uncaught ReferenceError: $ is not defined

It's because you haven't included the JQuery file as needed.

Hope this helps! Leo.