Hello, welcome to therichpost.com. In this post, I will tell you, How to add checkout button on product page woocommerce?  WordPress is the best cms and Woocommerce is the best Ecommerce plugin. WordPress hooks(add_action, add_filter) give us the power to edit or change the code without interruption into the files and this is the best thing about wordpress. 

Here is image to add checkout button on product page woocommerce:

Now, here is the working hook to add checkout button on product page woocommerce and you need to add this into your theme’s functions.php file:

function add_content_after_addtocart() {

// get the current post/product ID
$current_product_id = get_the_ID();

// get the product based on the ID
$product = wc_get_product( $current_product_id );

// get the "Checkout Page" URL
$checkout_url = WC()->cart->get_checkout_url();

// run only on simple products
if( $product->is_type( 'simple' ) ){

    <script>
        jQuery(function($) 
        {

               $(".custom-checkout-btn").on("click", function() 
                {
                   $(this).attr("href", function() 
                    {
                        return this.href + '&quantity=' + $('input.qty').val();
                    });

                });?>
        });
    </script>

    echo '<a href="'.$checkout_url.'?add-to-cart='.$current_product_id.'" class="single_add_to_cart_button button alt">Checkout</a>';
}
}
 add_action( 'woocommerce_after_add_to_cart_button', 'add_content_after_addtocart' );

 There are so many codes in woocommerce and i will let you know all. Please do comment if you any query             related  to   this post. Thank you. Therichpost.com