Gsyfuy

I'm using custom modules to show quantity increment/decrement in quantity box
using KnockoutJS.

Making custom modules for every folder is correct.but it nothing happpend, after click on increment/decrement button on product details page in magentov2.1.9.

I followed this link during this task:

https://magenticians.com/quantity-increment-decrement-magento-2/

what are missing from my side.

=> Go to your theme Folder and create file called addtocart.phtml and
past below code.

Quantity Increment and Decrement Button working fine by using below code

E.g :

app/design/frontend/Vendor/theme/Magento_Catalog/templates/product/view/addtocart.phtml

<?php

/**

 * Copyright © 2013-2017 Magento, Inc. All rights reserved.

 * See COPYING.txt for license details.

 */



// @codingStandardsIgnoreFile



/** @var $block MagentoCatalogBlockProductView */

?>

<?php $_product = $block->getProduct(); ?>

<?php $buttonTitle = __('Add to Cart'); ?>

<?php if ($_product->isSaleable()): ?>

<div class="box-tocart">

    <div class="fieldset">

        <?php if ($block->shouldRenderQuantity()): ?>

        <div class="field qty">

            <label class="label" for="qty"><span><?php /* @escapeNotVerified */ echo __('Qty') ?></span></label>

            <?php /*Add Plus Button */ ?>

             <input type='button' value='+' class='qtyplus' field='qty' />

            <div class="control">

                <input type="number"

                       name="qty"

                       id="qty"

                       maxlength="12"

                       value="<?php /* @escapeNotVerified */ echo $block->getProductDefaultQty() * 1 ?>"

                       title="<?php /* @escapeNotVerified */ echo __('Qty') ?>" class="input-text qty"

                       data-validate="<?php echo $block->escapeHtml(json_encode($block->getQuantityValidators())) ?>"

                       />

                <?php /*Add Minus Button */ ?>

            <input type='button' value='-' class='qtyminus' field='qty' />

            </div>

        </div>

        <?php endif; ?>

        <div class="actions">

            <button type="submit"

                    title="<?php /* @escapeNotVerified */ echo $buttonTitle ?>"

                    class="action primary tocart"

                    id="product-addtocart-button">

                <span><?php /* @escapeNotVerified */ echo $buttonTitle ?></span>

            </button>

            <?php echo $block->getChildHtml('', true) ?>

        </div>

    </div>

</div>

<?php endif; ?>

<script type="text/x-magento-init">

    {

        "#product_addtocart_form": {

            "Magento_Catalog/product/view/validation": {

                "radioCheckboxClosest": ".nested"

            }

        }

    }

</script>

<?php if (!$block->isRedirectToCartEnabled()) : ?>

<script type="text/x-magento-init">

    {

        "#product_addtocart_form": {

            "catalogAddToCart": {

                "bindSubmit": false

            }

        }

    }

</script>

<?php endif; ?>

<?php /*JS FOR +-*/ ?>

<script type="text/javascript">

        //&lt;![CDATA[

        require(['jquery'], function ($) {

            setTimeout(function () {

                // This button will increment the value

                jQuery('.qtyplus').click(function (e) {

                    // Stop acting like a button

                    e.preventDefault();

                    // Get the field name

                    fieldName = jQuery(this).attr('field');

                    // Get its current value

                    var currentVal = parseInt(jQuery('input[name=' + fieldName + ']').val());

                    // If is not undefined

                    if (!isNaN(currentVal)) {

                        // Increment

                        jQuery('input[name=' + fieldName + ']').val(currentVal + 1);

                    } else {

                        // Otherwise put a 0 there

                        jQuery('input[name=' + fieldName + ']').val(0);

                    }

                });

                // This button will decrement the value till 0

                jQuery(".qtyminus").click(function (e) {

                    // Stop acting like a button

                    e.preventDefault();

                    // Get the field name

                    fieldName = jQuery(this).attr('field');

                    // Get its current value

                    var currentVal = parseInt(jQuery('input[name=' + fieldName + ']').val());

                    // If it isn't undefined or its greater than 0

                    if (!isNaN(currentVal) && currentVal > 0) {

                        // Decrement one

                        jQuery('input[name=' + fieldName + ']').val(currentVal - 1);

                    } else {

                        // Otherwise put a 0 there

                        jQuery('input[name=' + fieldName + ']').val(0);

                    }

                });

            }, 100);

        });

        //]]&gt;

    </script>