Target WooCommerce submit button

Please copy the woo-commerce checkout.js and paste in your theme folder and add following code in your function.php

and after then you can change the checkout.js from your them.

function so_27023433_disable_checkout_script(){
    wp_dequeue_script( 'wc-checkout' );
    wp_enqueue_script('checkout',  get_template_directory_uri() . '/js/checkout.js', array(), '1.0.0', true );
}
add_action( 'wp_enqueue_scripts', 'so_27023433_disable_checkout_script' );