Magento 2 Javascript Widget which multiplies two values and stores the result in a Bundle Option Quantity

multiply.js

/**
 * Multiplies pages and copies and puts the result into the qty field
 */
define([
    'jquery',
    'underscore',
    'mage/template',
], function ($, _, mageTemplate, utils) {
    'use strict';

    $.widget('mage.ACMEProductMultiply', {
        /**
         * @private
         */
        _init: function initACMEProductMultiply() {
        },

        /**
         * @private
         */
        _create: function createACMEProductMultiply() {
            var wrapper = this.element,
                pages = $(this.options.pagesSelector, wrapper),
                copies = $(this.options.copiesSelector, wrapper);

            pages.on('change', this._onFactorQtyFieldChanged.bind(this));
            copies.on('change', this._onFactorQtyFieldChanged.bind(this));
        },

        _onFactorQtyFieldChanged: function onFactorQtyFieldChanges() {
            var wrapper = this.element,
                pages = $(this.options.pagesSelector, wrapper),
                copies = $(this.options.copiesSelector, wrapper),
                qty = $(this.options.qtyFieldSelector);

            qty.val(pages.val() * copies.val());
            qty.trigger('change');
        }
    });

    return $.mage.ACMEProductMultiply;
});

radio.html

<?php
/**
 * Copyright © 2015 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */

// @codingStandardsIgnoreFile

?>
<?php /* @var $block \Magento\Bundle\Block\Catalog\Product\View\Type\Bundle\Option\Radio */ ?>
<?php $_option = $block->getOption(); ?>
<?php $_selections = $_option->getSelections(); ?>
<?php $_default = $_option->getDefaultSelection(); ?>
<?php list($_defaultQty, $_canChangeQty) = $block->getDefaultValues(); ?>

<script type="text/x-magento-init">
    {
        "#qty-multi-<?php echo $_option->getId() ?>": {
            "ACMEProductMultiply": {
                "pagesSelector": "#bundle-option-<?php echo $_option->getId() ?>-qty-input-pages",
                "copiesSelector": "#bundle-option-<?php echo $_option->getId() ?>-qty-input-copies",
                "qtyFieldSelector": "#bundle-option-<?php echo $_option->getId() ?>-qty-input"
            }
        }
    }
</script>

<div class="field option <?php echo ($_option->getRequired()) ? ' required' : ''; ?>">
    <label class="label">
        <span><?php echo $block->escapeHtml($_option->getTitle()) ?></span>
    </label>

    <div class="control">
        <div class="nested options-list">
            <?php if ($block->showSingle()): ?>
                <?php echo $block->getSelectionTitlePrice($_selections[0]) ?>
                <input type="hidden"
                       class="bundle-option-<?php echo $_option->getId() ?>  product bundle option"
                       name="bundle_option[<?php echo $_option->getId() ?>]"
                       value="<?php echo $_selections[0]->getSelectionId() ?>"/>
            <?php else: ?>
                <?php if (!$_option->getRequired()): ?>
                    <div class="field choice">
                        <input type="radio"
                               class="radio product bundle option"
                               id="bundle-option-<?php echo $_option->getId() ?>"
                               name="bundle_option[<?php echo $_option->getId() ?>]"
                            <?php echo ($_default && $_default->isSalable()) ? '' : ' checked="checked" ' ?>
                               value=""/>
                        <label class="label" for="bundle-option-<?php echo $_option->getId() ?>">
                            <span><?php echo __('None') ?></span>
                        </label>
                    </div>
                <?php endif; ?>
                <?php foreach ($_selections as $_selection): ?>
                    <div class="field choice">
                        <input type="radio"
                               class="radio product bundle option change-container-classname"
                               id="bundle-option-<?php echo $_option->getId() ?>-<?php echo $_selection->getSelectionId() ?>"
                            <?php if ($_option->getRequired()) echo 'data-validate="{\'validate-one-required-by-name\':true}"' ?>
                               name="bundle_option[<?php echo $_option->getId() ?>]"
                            <?php if ($block->isSelected($_selection)) echo ' checked="checked"' ?>
                            <?php if (!$_selection->isSaleable()) echo ' disabled="disabled"' ?>
                               value="<?php echo $_selection->getSelectionId() ?>"/>
                        <label class="label"
                               for="bundle-option-<?php echo $_option->getId() ?>-<?php echo $_selection->getSelectionId() ?>">
                            <span><?php echo $block->getSelectionTitlePrice($_selection) ?></span>
                        </label>
                    </div>
                <?php endforeach; ?>
                <div id="bundle-option-<?php echo $_option->getId() ?>-container"></div>
            <?php endif; ?>
            <div class="qty-multi-wrapper" id="qty-multi-<?php echo $_option->getId() ?>">
                <div class="field qty qty-holder">
                    <label class="label" for="bundle-option-<?php echo $_option->getId() ?>-qty-input-pages">
                        <span><?php echo __('Pages') ?></span>
                    </label>

                    <div class="control">
                        <input
                            id="bundle-option-<?php echo $_option->getId() ?>-qty-input-pages"
                            class="input-text qty-pages"
                            type="number"
                            name="bundle_option_qty_pages[<?php echo $_option->getId() ?>]"
                            value="1"/>
                    </div>
                </div>
                <div class="field qty qty-holder">
                    <label class="label" for="bundle-option-<?php echo $_option->getId() ?>-qty-input-copies">
                        <span><?php echo __('Copies') ?></span>
                    </label>

                    <div class="control">
                        <input
                            id="bundle-option-<?php echo $_option->getId() ?>-qty-input-copies"
                            class="input-text qty-copies"
                            type="number"
                            name="bundle_option_qty_copies[<?php echo $_option->getId() ?>]"
                            value="<?php echo $_defaultQty ?>"/>
                    </div>
                </div>
            </div>
            <input <?php if (!$_canChangeQty) echo ' disabled="disabled"' ?>
                id="bundle-option-<?php echo $_option->getId() ?>-qty-input"
                class="input-text qty<?php if (!$_canChangeQty) echo ' qty-disabled' ?>"
                type="hidden"
                name="bundle_option_qty[<?php echo $_option->getId() ?>]"
                value="<?php echo $_defaultQty ?>"/>
        </div>
    </div>
</div>