WooCommerce: Add Privacy Policy checkbox to checkout form

woocommerce-add-privacy-policy-checkbox-to-checkout.php

/**
 * Add a privacy policy checkbox on the checkout form
 *
 * @author Wil Brown zeropointdevelopment.com
 */
function zpd_add_checkout_privacy_policy() {

    woocommerce_form_field( 'privacy_policy', array(
        'type'          => 'checkbox',
        'class'         => array('form-row privacy'),
        'label_class'   => array('woocommerce-form__label woocommerce-form__label-for-checkbox checkbox'),
        'input_class'   => array('woocommerce-form__input woocommerce-form__input-checkbox input-checkbox'),
        'required'      => true,
        'label'         => 'I have read and agree with the <a href="' . get_privacy_policy_url() . '">Privacy Policy</a>',
    ));

}
add_action( 'woocommerce_review_order_before_submit',  'zpd_add_checkout_privacy_policy', 9 );

// Show notice if customer doesn't check the box (required)

/**
 * Show notice if customer doesn't check the new privacy policy checkbox
 *
 * @author Wil Brown zeropointdevelopment.com
 */
function zpd_privacy_not_agreed() {
    if ( ! (int) isset( $_POST['privacy_policy'] ) ) {
        wc_add_notice( __( 'Please read and accept the <strong>privacy policy</strong> to proceed with your order.' ), 'error' );
    }
}
add_action( 'woocommerce_checkout_process', 'zpd_privacy_not_agreed' );