Trigger update_checkout with custom select field in Woocommerce

Question

Problem: The jQuery code doesn't triggers "update_checkout".

I have added a custom select field on order review table for customers to choose the tip amount as shown:

I want to trigger update_checkout when then select value changes, but it doesn't happen. If I select the shipping method it does triggers "update_checkout" and updates the amount percentage correctly.

HTML:

<tr class="propina">
        <th id="propina_field">Propina</th>
            <td>
                <span class="woocommerce-input-wrapper">
                    <select name="propina" id="propina" class="select" data-placeholder="">
                        <option value="0">0</option>
                        <option value="1">1%</option>
                        <option value="2">2%</option>
                        <option value="3">3%</option>
                        <option value="5">5%</option>
                        <option value="7">7%</option>
                        <option selected value="10">10%</option>
                    </select>
                </span>
            </td>                           
</tr>

functions.php:

add_action( 'wp_head', 'woocommerce_tip' );
function woocommerce_tip() {
    ?>
    <script type="text/javascript">
    jQuery( document ).ready(function( $ ) {
        $('#propina').change(function(){
            jQuery('body').trigger('update_checkout');
        });
    });
    </script>
    <?php
}

Answer 1

Updated

To test your code like in your question screenshot, I have used the following to get the same select field displayed in the right location:

add_action('woocommerce_review_order_before_order_total', 'review_order_tip_line');
function review_order_tip_line() {
    ?>
    <tr class="propina"><th id="propina_field">Propina</th><td><span class="woocommerce-input-wrapper">
        <select name="propina" id="propina" class="select" data-placeholder="">
            <option value="0">0</option>
            <option value="1">1%</option>
            <option value="2">2%</option>
            <option value="3">3%</option>
            <option value="5">5%</option>
            <option value="7">7%</option>
            <option selected value="10">10%</option>
        </select>
    </td></span></tr>
    <?php
}

Then here is your revisited jQuery code:

add_action( 'wp_footer', 'woocommerce_tip_script' );
function woocommerce_tip_script() {
    // Only on checkout page
    if( ! is_checkout() ) return;
    ?>
    <script type="text/javascript">
    jQuery(function($){
        // On 'select#propina' change (live event)
        $('form.woocommerce-checkout').on( 'change', 'select#propina', function(){
            // Set the select value in a variable
            var a = $(this).val();

            // Update checkout event
            $('body').trigger('update_checkout');

            // Restoring the chosen option value
            $('select#propina option[value='+a+']').prop('selected', true);

            // Just for testing (To be removed)
            console.log('trigger "update_checkout"');

            // Once checkout has been updated
            $('body').on('updated_checkout', function(){
                // Restoring the chosen option value
                $('select#propina option[value='+a+']').prop('selected', true);

                // Just for testing (To be removed)
                console.log('"updated_checkout" event, restore selected option value: '+a);
            });
        });
    })
    </script>
    <?php
}

Code goes in function.php file of your active child theme (or active theme). Tested and work.