Display a checkbox that add a fee in Woocommerce checkout page

Question

In Woocommerce checkout page, I\'am trying to add a check box on checkout page

I have referred to these articles

woocommerce custom checkout field to add fe

Answer 1

You really need to use Wordpress Ajax with WC_sessions to make it work like in "Add a checkout checkbox field that enable a percentage fee in Woocommerce" answer thread.

Here is your revisited code:

// Display the custom checkbow field in checkout
add_action( 'woocommerce_review_order_before_order_total', 'fee_installment_checkbox_field', 20 );
function fee_installment_checkbox_field(){
    echo '';

    woocommerce_form_field( 'installment_fee', array(
        'type'          => 'checkbox',
        'class'         => array('installment-fee form-row-wide'),
        'label'         => __('Support installation'),
        'placeholder'   => __(''),
    ), WC()->session->get('installment_fee') ? '1' : '' );

    echo '';
}

// jQuery - Ajax script
add_action( 'wp_footer', 'checkout_fee_script' );
function checkout_fee_script() {
    // Only on Checkout
    if( is_checkout() && ! is_wc_endpoint_url() ) :

    if( WC()->session->__isset('installment_fee') )
        WC()->session->__unset('installment_fee')
    ?>
    
    session->set('installment_fee', ($_POST['installment_fee'] ? true : false) );
    }
    die();
}


// Add a custom calculated fee conditionally
add_action( 'woocommerce_cart_calculate_fees', 'set_installment_fee' );
function set_installment_fee( $cart ){
    if ( is_admin() && ! defined('DOING_AJAX') || ! is_checkout() )
        return;

    if ( did_action('woocommerce_cart_calculate_fees') >= 2 )
        return;

    if ( 1 == WC()->session->get('installment_fee') ) {
        $items_count = WC()->cart->get_cart_contents_count();
        $fee_label   = sprintf( __( "Support installation %s %s" ), '×', $items_count );
        $fee_amount  = 50000 * $items_count;
        WC()->cart->add_fee( $fee_label, $fee_amount );
    }
}

add_filter( 'woocommerce_form_field' , 'remove_optional_txt_from_installment_checkbox', 10, 4 );
function remove_optional_txt_from_installment_checkbox( $field, $key, $args, $value ) {
    // Only on checkout page for Order notes field
    if( 'installment_fee' === $key && is_checkout() ) {
        $optional = ' (' . esc_html__( 'optional', 'woocommerce' ) . ')';
        $field = str_replace( $optional, '', $field );
    }
    return $field;
}

Code goes in functions.php file of your active child theme (or active theme). Tested and works on Woocommerce version 3.6.5 with Storefront theme.