How to Show Out of Stock Options for Configurable Products Dropdown in Magento 2

Hello Magento Friends,

Today I am going to explain How to Show Out of Stock Options for Configurable Products Dropdown in Magento 2.

For configurable products, if any option is out of stock, it does not display on the product page. For example, if you sell tshirt with sizes S, M, L, and XL and from them L is sold out, it is not displayed to customers. Only S, M, and XL are displayed. Instead of that, you can display out of stock products in the dropdown with grey color so that customers are aware of your offerings. 

You can even notify customers when the product is back in stock with the help of Magento 2 Out of Stock Notification Extension. The Magento 2 store owners can manage out of stock products list and add more quantity.

For now, let’s look at the steps to Show Out of Stock Options for Configurable Products Dropdown in Magento 2.

Steps to Show Out of Stock Options for Configurable Products Dropdown in Magento 2:

Step 1: First, we need to create a “di.xml” file inside the etc directory of our extension

app\code\Vendor\Extension\etc

Now, add the below code

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Swatches\Block\Product\Renderer\Configurable" type="Vendor\Extension\Block\Product\View\Type\Configurable"/>
</config>

Step 2: Then, we need to create a “Configurable.php” file inside the extension at the following path.

app\code\Vendor\Extension\Block\Product\View\Type

And add the following code

<?php
namespace Vendor\Extension\Block\Product\View\Type;

use Magento\Catalog\Block\Product\Context;
use Magento\Catalog\Helper\Product as CatalogProduct;
use Magento\ConfigurableProduct\Helper\Data;
use Magento\ConfigurableProduct\Model\ConfigurableAttributeData;
use Magento\Customer\Helper\Session\CurrentCustomer;
use Magento\Framework\Json\EncoderInterface;
use Magento\Framework\Pricing\PriceCurrencyInterface;
use Magento\Catalog\Model\Product;
use Magento\Framework\Stdlib\ArrayUtils;
use Magento\Store\Model\ScopeInterface;
use Magento\Swatches\Helper\Data as SwatchData;
use Magento\Swatches\Helper\Media;
use Magento\Swatches\Model\Swatch;

class Configurable extends \Magento\Swatches\Block\Product\Renderer\Configurable 
{

     public function __construct(
        Context $context,
        ArrayUtils $arrayUtils,
        EncoderInterface $jsonEncoder,
        Data $helper,
        CatalogProduct $catalogProduct,
        CurrentCustomer $currentCustomer,
        PriceCurrencyInterface $priceCurrency,
        ConfigurableAttributeData $configurableAttributeData,
        SwatchData $swatchHelper,
        Media $swatchMediaHelper,
        array $data = []
    ){
         $this->swatchHelper = $swatchHelper;
        $this->swatchMediaHelper = $swatchMediaHelper;
         parent::__construct(
            $context,
            $arrayUtils,
            $jsonEncoder,
            $helper,
            $catalogProduct,
            $currentCustomer,
            $priceCurrency,
            $configurableAttributeData,
            $swatchHelper,
            $swatchMediaHelper,
            $data
        );
    }

    public function getJsonConfig() {
        $store = $this->getCurrentStore();
        $currentProduct = $this->getProduct();

        $regularPrice = $currentProduct->getPriceInfo()->getPrice('regular_price');
        $finalPrice = $currentProduct->getPriceInfo()->getPrice('final_price');

        $options = $this->getOptions($currentProduct, $this->getAllowProducts());
        $attributesData = $this->configurableAttributeData->getAttributesData($currentProduct, $options);
       
        $config = [
            'attributes' => $attributesData['attributes'],
            'template' => str_replace('%s', '<%- data.price %>', $store->getCurrentCurrency()->getOutputFormat()),
            'optionPrices' => $this->getOptionPrices(),
            'prices' => [
                'oldPrice' => [
                    'amount' => $this->_registerJsPrice($regularPrice->getAmount()->getValue()),
                ],
                'basePrice' => [
                    'amount' => $this->_registerJsPrice(
                        $finalPrice->getAmount()->getBaseAmount()
                    ),
                ],
                'finalPrice' => [
                    'amount' => $this->_registerJsPrice($finalPrice->getAmount()->getValue()),

                ],
            ],
            'productId' => $currentProduct->getId(),
            'is_salable' => $this->getIsSalable($this->getAllowProducts()),
            'chooseText' => __('Choose an Option....'),
            'images' => isset($options['images']) ? $options['images'] : [],
            'index' => isset($options['index']) ? $options['index'] : [],
        ]; 
        

        if ($currentProduct->hasPreconfiguredValues() && !empty($attributesData['defaultValues'])) {
            $config['defaultValues'] = $attributesData['defaultValues'];
        }

        $config = array_merge($config, $this->_getAdditionalConfig());

        return $this->jsonEncoder->encode($config);
    }
   
    public function getOptions($currentProduct, $allowedProducts)
    {
        $options = [];
        $allowAttributes = $this->getAllowAttributes($currentProduct);
	    foreach ($allowedProducts as $product) {
            $productId = $product->getId();
            foreach ($allowAttributes as $attribute) {
                $productAttribute = $attribute->getProductAttribute();
                $productAttributeId = $productAttribute->getId();
                $attributeValue = $product->getData($productAttribute->getAttributeCode());
               $options[$productAttributeId][$attributeValue][] = $productId;
               $options['index'][$productId][$productAttributeId] = $attributeValue;
            }
        }
        return $options;
    }
    public function getIsSalable($allowedProducts)
    {
        $options = [];
    	$allowAttributes = $this->getAllowAttributes($allowedProducts);
	    foreach ($allowedProducts as $product) {
		    foreach ($allowAttributes as $attribute) {
                	$productAttribute = $attribute->getProductAttribute();
                	$productAttributeId = $productAttribute->getId();
                	$attributeValue = $product->getData($productAttribute->getAttributeCode());
                	if (!$product->isSalable()) {
                		$options[] = array("product_id"=>$product->getId(),"attribute_value"=>$attributeValue,"product_attribute_id"=>$productAttributeId);
                	}
            }
        }
       
        return $options;
    }

}

Step 3: After that, we need to create a “requirejs-config.js” file inside the extension on the following path.

app\code\Vendor\Extension\view\frontend

Now, add the below code

var config = {
    map: {
        '*': {
            configurable:'Vendor_Extension/js/configurable',
        }
    }
};

Step 4: After that, we need to create a “configurable.js” file inside the extension on the following path.

app\code\Vendor\Extension\view\frontend\web\js

And add the code as follows

define([
    'jquery',
    'underscore',
    'mage/template',
    'mage/translate',
    'priceUtils',
    'priceBox',
    'jquery-ui-modules/widget',
    'jquery/jquery.parsequery'
], function ($, _, mageTemplate, $t, priceUtils) {
    'use strict';

    $.widget('mage.configurable', {
        options: {
            superSelector: '.super-attribute-select',
            selectSimpleProduct: '[name="selected_configurable_option"]',
            priceHolderSelector: '.price-box',
            spConfig: {},
            state: {},
            priceFormat: {},
            optionTemplate: '<%- data.label %>' +
            '<% if (typeof data.finalPrice.value !== "undefined") { %>' +
            ' <%- data.finalPrice.formatted %>' +
            '<% } %>',
            mediaGallerySelector: '[data-gallery-role=gallery-placeholder]',
            mediaGalleryInitial: null,
            slyOldPriceSelector: '.sly-old-price',
            normalPriceLabelSelector: '.normal-price .price-label',

            /**
             * Defines the mechanism of how images of a gallery should be
             * updated when user switches between configurations of a product.
             *
             * As for now value of this option can be either 'replace' or 'prepend'.
             *
             * @type {String}
             */
            gallerySwitchStrategy: 'replace',
            tierPriceTemplateSelector: '#tier-prices-template',
            tierPriceBlockSelector: '[data-role="tier-price-block"]',
            tierPriceTemplate: ''
        },

        /**
         * Creates widget
         * @private
         */
        _create: function () {
            // Initial setting of various option values
            this._initializeOptions();

            // Override defaults with URL query parameters and/or inputs values
            this._overrideDefaults();

            // Change events to check select reloads
            this._setupChangeEvents();

            // Fill state
            this._fillState();

            // Setup child and prev/next settings
            this._setChildSettings();

            // Setup/configure values to inputs
            this._configureForValues();

            $(this.element).trigger('configurable.initialized');
        },

        /**
         * Initialize tax configuration, initial settings, and options values.
         * @private
         */
        _initializeOptions: function () {
            var options = this.options,
                gallery = $(options.mediaGallerySelector),
                priceBoxOptions = $(this.options.priceHolderSelector).priceBox('option').priceConfig || null;

            if (priceBoxOptions && priceBoxOptions.optionTemplate) {
                options.optionTemplate = priceBoxOptions.optionTemplate;
            }

            if (priceBoxOptions && priceBoxOptions.priceFormat) {
                options.priceFormat = priceBoxOptions.priceFormat;
            }
            options.optionTemplate = mageTemplate(options.optionTemplate);
            options.tierPriceTemplate = $(this.options.tierPriceTemplateSelector).html();

            options.settings = options.spConfig.containerId ?
                $(options.spConfig.containerId).find(options.superSelector) :
                $(options.superSelector);

            options.values = options.spConfig.defaultValues || {};
            options.parentImage = $('[data-role=base-image-container] img').attr('src');

            this.inputSimpleProduct = this.element.find(options.selectSimpleProduct);

            gallery.data('gallery') ?
                this._onGalleryLoaded(gallery) :
                gallery.on('gallery:loaded', this._onGalleryLoaded.bind(this, gallery));

        },

        /**
         * Override default options values settings with either URL query parameters or
         * initialized inputs values.
         * @private
         */
        _overrideDefaults: function () {
            var hashIndex = window.location.href.indexOf('#');

            if (hashIndex !== -1) {
                this._parseQueryParams(window.location.href.substr(hashIndex + 1));
            }

            if (this.options.spConfig.inputsInitialized) {
                this._setValuesByAttribute();
            }

            this._setInitialOptionsLabels();
        },

        /**
         * Parse query parameters from a query string and set options values based on the
         * key value pairs of the parameters.
         * @param {*} queryString - URL query string containing query parameters.
         * @private
         */
        _parseQueryParams: function (queryString) {
            var queryParams = $.parseQuery({
                query: queryString
            });

            $.each(queryParams, $.proxy(function (key, value) {
                this.options.values[key] = value;
            }, this));
        },

        /**
         * Override default options values with values based on each element's attribute
         * identifier.
         * @private
         */
        _setValuesByAttribute: function () {
            this.options.values = {};
            $.each(this.options.settings, $.proxy(function (index, element) {
                var attributeId;

                if (element.value) {
                    attributeId = element.id.replace(/[a-z]*/, '');
                    this.options.values[attributeId] = element.value;
                }
            }, this));
        },

        /**
         * Set additional field with initial label to be used when switching between options with different prices.
         * @private
         */
        _setInitialOptionsLabels: function () {
            $.each(this.options.spConfig.attributes, $.proxy(function (index, element) {
                $.each(element.options, $.proxy(function (optIndex, optElement) {
                    this.options.spConfig.attributes[index].options[optIndex].initialLabel = optElement.label;
                }, this));
            }, this));
        },

        /**
         * Set up .on('change') events for each option element to configure the option.
         * @private
         */
        _setupChangeEvents: function () {
            $.each(this.options.settings, $.proxy(function (index, element) {
                $(element).on('change', this, this._configure);
            }, this));
        },

        /**
         * Iterate through the option settings and set each option's element configuration,
         * attribute identifier. Set the state based on the attribute identifier.
         * @private
         */
        _fillState: function () {
            $.each(this.options.settings, $.proxy(function (index, element) {
                var attributeId = element.id.replace(/[a-z]*/, '');

                if (attributeId && this.options.spConfig.attributes[attributeId]) {
                    element.config = this.options.spConfig.attributes[attributeId];
                    element.attributeId = attributeId;
                    this.options.state[attributeId] = false;
                }
            }, this));
        },

        /**
         * Set each option's child settings, and next/prev option setting. Fill (initialize)
         * an option's list of selections as needed or disable an option's setting.
         * @private
         */
        _setChildSettings: function () {
            var childSettings = [],
                settings = this.options.settings,
                index = settings.length,
                option;

            while (index--) {
                option = settings[index];

                if (index) {
                    option.disabled = true;
                } else {
                    this._fillSelect(option);
                }

                _.extend(option, {
                    childSettings: childSettings.slice(),
                    prevSetting: settings[index - 1],
                    nextSetting: settings[index + 1]
                });

                childSettings.push(option);
            }
        },

        /**
         * Setup for all configurable option settings. Set the value of the option and configure
         * the option, which sets its state, and initializes the option's choices, etc.
         * @private
         */
        _configureForValues: function () {
            if (this.options.values) {
                this.options.settings.each($.proxy(function (index, element) {
                    var attributeId = element.attributeId;

                    element.value = this.options.values[attributeId] || '';
                    this._configureElement(element);
                }, this));
            }
        },

        /**
         * Event handler for configuring an option.
         * @private
         * @param {Object} event - Event triggered to configure an option.
         */
        _configure: function (event) {
            event.data._configureElement(this);
        },

        /**
         * Configure an option, initializing it's state and enabling related options, which
         * populates the related option's selection and resets child option selections.
         * @private
         * @param {*} element - The element associated with a configurable option.
         */
        _configureElement: function (element) {
            this.simpleProduct = this._getSimpleProductId(element);

            if (element.value) {
                this.options.state[element.config.id] = element.value;

                if (element.nextSetting) {
                    element.nextSetting.disabled = false;
                    this._fillSelect(element.nextSetting);
                    this._resetChildren(element.nextSetting);
                } else {
                    if (!!document.documentMode) { //eslint-disable-line
                        this.inputSimpleProduct.val(element.options[element.selectedIndex].config.allowedProducts[0]);
                    } else {
                        this.inputSimpleProduct.val(element.selectedOptions[0].config.allowedProducts[0]);
                    }
                }
            } else {
                this._resetChildren(element);
            }

            this._reloadPrice();
            this._displayRegularPriceBlock(this.simpleProduct);
            this._displayTierPriceBlock(this.simpleProduct);
            this._displayNormalPriceLabel();
            this._changeProductImage();
        },

        /**
         * Change displayed product image according to chosen options of configurable product
         *
         * @private
         */
        _changeProductImage: function () {
            var images,
                initialImages = this.options.mediaGalleryInitial,
                galleryObject = $(this.options.mediaGallerySelector).data('gallery');

            if (!galleryObject) {
                return;
            }

            images = this.options.spConfig.images[this.simpleProduct];

            if (images) {
                images = this._sortImages(images);

                if (this.options.gallerySwitchStrategy === 'prepend') {
                    images = images.concat(initialImages);
                }

                images = $.extend(true, [], images);
                images = this._setImageIndex(images);

                galleryObject.updateData(images);

                $(this.options.mediaGallerySelector).AddFotoramaVideoEvents({
                    selectedOption: this.simpleProduct,
                    dataMergeStrategy: this.options.gallerySwitchStrategy
                });
            } else {
                galleryObject.updateData(initialImages);
                $(this.options.mediaGallerySelector).AddFotoramaVideoEvents();
            }

        },

        /**
         * Sorting images array
         *
         * @private
         */
        _sortImages: function (images) {
            return _.sortBy(images, function (image) {
                return image.position;
            });
        },

        /**
         * Set correct indexes for image set.
         *
         * @param {Array} images
         * @private
         */
        _setImageIndex: function (images) {
            var length = images.length,
                i;

            for (i = 0; length > i; i++) {
                images[i].i = i + 1;
            }

            return images;
        },

        /**
         * For a given option element, reset all of its selectable options. Clear any selected
         * index, disable the option choice, and reset the option's state if necessary.
         * @private
         * @param {*} element - The element associated with a configurable option.
         */
        _resetChildren: function (element) {
            if (element.childSettings) {
                _.each(element.childSettings, function (set) {
                    set.selectedIndex = 0;
                    set.disabled = true;
                });

                if (element.config) {
                    this.options.state[element.config.id] = false;
                }
            }
        },

        /**
         * Populates an option's selectable choices.
         * @private
         * @param {*} element - Element associated with a configurable option.
         */
        _fillSelect: function (element) {
            var attributeId = element.id.replace(/[a-z]*/, ''),
                options = this._getAttributeOptions(attributeId),
                prevConfig,
                index = 1,
                allowedProducts,
                allowedProductsByOption,
                allowedProductsAll,
                i,
                j,
                finalPrice = parseFloat(this.options.spConfig.prices.finalPrice.amount),
                optionFinalPrice,
                optionPriceDiff,
                optionPrices = this.options.spConfig.optionPrices,
                allowedOptions = [],
                indexKey,
                allowedProductMinPrice,
                allowedProductsAllMinPrice;

            this._clearSelect(element);
            element.options[0] = new Option('', '');
            element.options[0].innerHTML = this.options.spConfig.chooseText;
            prevConfig = false;

            if (element.prevSetting) {
                prevConfig = element.prevSetting.options[element.prevSetting.selectedIndex];
            }

            if (options) {
                for (indexKey in this.options.spConfig.index) {
                    /* eslint-disable max-depth */
                    if (this.options.spConfig.index.hasOwnProperty(indexKey)) {
                        allowedOptions = allowedOptions.concat(_.values(this.options.spConfig.index[indexKey]));
                    }
                }

                if (prevConfig) {
                   var allowedProductsByOption = {};
                   var allowedProductsAll = [];

                    for (i = 0; i < options.length; i++) {
                        /* eslint-disable max-depth */
                        for (j = 0; j < options[i].products.length; j++) {
                            // prevConfig.config can be undefined
                            if (prevConfig.config &&
                                prevConfig.config.allowedProducts &&
                                prevConfig.config.allowedProducts.indexOf(options[i].products[j]) > -1) {
                                if (!allowedProductsByOption[i]) {
                                    allowedProductsByOption[i] = [];
                                }
                                allowedProductsByOption[i].push(options[i].products[j]);
                                allowedProductsAll.push(options[i].products[j]);
                            }
                        }
                    }

                    if (typeof allowedProductsAll[0] !== 'undefined' &&
                        typeof optionPrices[allowedProductsAll[0]] !== 'undefined') {
                        allowedProductsAllMinPrice = this._getAllowedProductWithMinPrice(allowedProductsAll);
                        finalPrice = parseFloat(optionPrices[allowedProductsAllMinPrice].finalPrice.amount);
                    }
                }

                for (i = 0; i < options.length; i++) {
                    allowedProducts = prevConfig ? allowedProductsByOption[i] : options[i].products.slice(0);
                    optionPriceDiff = 0;
		    if(allowedProducts){
                    if (typeof optionPrices[allowedProducts[0]] !== 'undefined') {
                        allowedProductMinPrice = this._getAllowedProductWithMinPrice(allowedProducts);
                        optionFinalPrice = parseFloat(optionPrices[allowedProductMinPrice].finalPrice.amount);
                        optionPriceDiff = optionFinalPrice - finalPrice;
                        options[i].label = options[i].initialLabel;

                        if (optionPriceDiff !== 0) {
                            options[i].label += ' ' + priceUtils.formatPrice(
                                optionPriceDiff,
                                this.options.priceFormat,
                                true
                            );
                        }
                    }
                   }
		    if(allowedProducts){
                    if (allowedProducts.length > 0 || _.include(allowedOptions, options[i].id)) {
                        options[i].allowedProducts = allowedProducts;
                        element.options[index] = new Option(this._getOptionLabel(options[i]), options[i].id);
                        /*---Customize Start----*/
                        var custom_option=[];
                        for(var p = 0; p < this.options.spConfig.is_salable.length; p++){
                            console.log(allowedProducts[0]+"-"+this.options.spConfig.is_salable[p]['product_id']);
                        	if(this.options.spConfig.is_salable[p]['attribute_value']){
                        		if(options[i].id==this.options.spConfig.is_salable[p]['attribute_value'] && allowedProducts[0]==this.options.spConfig.is_salable[p]['product_id']){
		                		custom_option=options[i].id;
		        	  	    }
                	  	}
                 	 }	
 			        /*---Customize End----*/
			
			 if (typeof options[i].price !== 'undefined') {
                            element.options[index].setAttribute('price', options[i].price);
                        }
                        console.log("length :"+allowedProducts.length+"-"+custom_option+"=="+options[i].id);
                        if (allowedProducts.length === 0) {
                            element.options[index].disabled = true;
                        }else if(allowedProducts.length === 1 && custom_option==options[i].id){
                            element.options[index].disabled = true;
                        }

                        element.options[index].config = options[i];
                        index++;
                    }
			}

                    /* eslint-enable max-depth */
                }
            }
        },

        /**
         * Generate the label associated with a configurable option. This includes the option's
         * label or value and the option's price.
         * @private
         * @param {*} option - A single choice among a group of choices for a configurable option.
         * @return {String} The option label with option value and price (e.g. Black +1.99)
         */
        _getOptionLabel: function (option) {
            return option.label;
        },

        /**
         * Removes an option's selections.
         * @private
         * @param {*} element - The element associated with a configurable option.
         */
        _clearSelect: function (element) {
            var i;

            for (i = element.options.length - 1; i >= 0; i--) {
                element.remove(i);
            }
        },

        /**
         * Retrieve the attribute options associated with a specific attribute Id.
         * @private
         * @param {Number} attributeId - The id of the attribute whose configurable options are sought.
         * @return {Object} Object containing the attribute options.
         */
        _getAttributeOptions: function (attributeId) {
            if (this.options.spConfig.attributes[attributeId]) {
                return this.options.spConfig.attributes[attributeId].options;
            }
        },

        /**
         * Reload the price of the configurable product incorporating the prices of all of the
         * configurable product's option selections.
         */
        _reloadPrice: function () {
            $(this.options.priceHolderSelector).trigger('updatePrice', this._getPrices());
        },

        /**
         * Get product various prices
         * @returns {{}}
         * @private
         */
        _getPrices: function () {
            var prices = {},
                elements = _.toArray(this.options.settings),
                allowedProduct;

            _.each(elements, function (element) {
                var selected = element.options[element.selectedIndex],
                    config = selected && selected.config,
                    priceValue = {};

                if (config && config.allowedProducts.length === 1) {
                    priceValue = this._calculatePrice(config);
                } else if (element.value) {
                    allowedProduct = this._getAllowedProductWithMinPrice(config.allowedProducts);
                    priceValue = this._calculatePrice({
                        'allowedProducts': [
                            allowedProduct
                        ]
                    });
                }

                if (!_.isEmpty(priceValue)) {
                    prices.prices = priceValue;
                }
            }, this);

            return prices;
        },

        /**
         * Get product with minimum price from selected options.
         *
         * @param {Array} allowedProducts
         * @returns {String}
         * @private
         */
        _getAllowedProductWithMinPrice: function (allowedProducts) {
            var optionPrices = this.options.spConfig.optionPrices,
                product = {},
                optionMinPrice, optionFinalPrice;

            _.each(allowedProducts, function (allowedProduct) {
                optionFinalPrice = parseFloat(optionPrices[allowedProduct].finalPrice.amount);

                if (_.isEmpty(product) || optionFinalPrice < optionMinPrice) {
                    optionMinPrice = optionFinalPrice;
                    product = allowedProduct;
                }
            }, this);

            return product;
        },

        /**
         * Returns prices for configured products
         *
         * @param {*} config - Products configuration
         * @returns {*}
         * @private
         */
        _calculatePrice: function (config) {
            var displayPrices = $(this.options.priceHolderSelector).priceBox('option').prices,
                newPrices = this.options.spConfig.optionPrices[_.first(config.allowedProducts)];

            _.each(displayPrices, function (price, code) {
                if (newPrices[code]) {
                    displayPrices[code].amount = newPrices[code].amount - displayPrices[code].amount;
                }
            });

            return displayPrices;
        },

        /**
         * Returns Simple product Id
         *  depending on current selected option.
         *
         * @private
         * @param {HTMLElement} element
         * @returns {String|undefined}
         */
        _getSimpleProductId: function (element) {
            // TODO: Rewrite algorithm. It should return ID of
            //        simple product based on selected options.
            var allOptions = element.config.options,
                value = element.value,
                config;

            config = _.filter(allOptions, function (option) {
                return option.id === value;
            });
            config = _.first(config);

            return _.isEmpty(config) ?
                undefined :
                _.first(config.allowedProducts);

        },

        /**
         * Show or hide regular price block
         *
         * @param {*} optionId
         * @private
         */
        _displayRegularPriceBlock: function (optionId) {
            var shouldBeShown = true;

            _.each(this.options.settings, function (element) {
                if (element.value === '') {
                    shouldBeShown = false;
                }
            });

            if (shouldBeShown &&
                this.options.spConfig.optionPrices[optionId].oldPrice.amount !==
                this.options.spConfig.optionPrices[optionId].finalPrice.amount
            ) {
                $(this.options.slyOldPriceSelector).show();
            } else {
                $(this.options.slyOldPriceSelector).hide();
            }

            $(document).trigger('updateMsrpPriceBlock',
                [
                    optionId,
                    this.options.spConfig.optionPrices
                ]
            );
        },

        /**
         * Show or hide normal price label
         *
         * @private
         */
        _displayNormalPriceLabel: function () {
            var shouldBeShown = false;

            _.each(this.options.settings, function (element) {
                if (element.value === '') {
                    shouldBeShown = true;
                }
            });

            if (shouldBeShown) {
                $(this.options.normalPriceLabelSelector).show();
            } else {
                $(this.options.normalPriceLabelSelector).hide();
            }
        },

        /**
         * Callback which fired after gallery gets initialized.
         *
         * @param {HTMLElement} element - DOM element associated with gallery.
         */
        _onGalleryLoaded: function (element) {
            var galleryObject = element.data('gallery');

            this.options.mediaGalleryInitial = galleryObject.returnCurrentImages();
        },

        /**
         * Show or hide tier price block
         *
         * @param {*} optionId
         * @private
         */
        _displayTierPriceBlock: function (optionId) {
            var options, tierPriceHtml;

            if (typeof optionId != 'undefined' &&
                this.options.spConfig.optionPrices[optionId].tierPrices != [] // eslint-disable-line eqeqeq
            ) {
                options = this.options.spConfig.optionPrices[optionId];

                if (this.options.tierPriceTemplate) {
                    tierPriceHtml = mageTemplate(this.options.tierPriceTemplate, {
                        'tierPrices': options.tierPrices,
                        '$t': $t,
                        'currencyFormat': this.options.spConfig.currencyFormat,
                        'priceUtils': priceUtils
                    });
                    $(this.options.tierPriceBlockSelector).html(tierPriceHtml).show();
                }
            } else {
                $(this.options.tierPriceBlockSelector).hide();
            }
        }
    });

    return $.mage.configurable;
});

Step 5: After that, from the Magento Admin Panel navigate to,

Stores →  Configuration →  Catalog →  Inventory → Stock Options 

Set “Yes” to the “Display Out of Stock Products” field.

Once you implement all the above steps, the Out of Stock Options will be displayed for the Configurable Products Dropdown as shown below.

Conclusion:

This way you can Show Out of Stock Options for Configurable Products Dropdown in Magento 2. Moreover, show out of stock product price for the awareness of customers. If you have any queries, let me know in the comment part. Do share the article with your friends and colleagues. Stay updated with us!

Happy Coding!