Mryntu

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>