TypeError: target.extend is not a function

Question

I need to change some logic formAddressDataToQuoteAddress() from vendor\magento\module-checkout\view\frontend\web\js\model\address-converter.js

I have referred the Magento docs and written this code and i am getting this error

TypeError: target.extend is not a function

app\code\Module\Checkout\view\frontend\requirejs-config.js

   var config = {
          config: {
              mixins: {
                  'Magento_Checkout/js/model/address-converter': {
                      'Perficient_Checkout/js/model/address-converter': true
                  }
              }
         } };

app\code\Module\Checkout\view\frontend\web\js\model\address-converter.js

define(function () {
    'use strict';

    var mixin = {
        formAddressDataToQuoteAddress: function (addressData) {
            return addressData;
        }
    };
    return function (target) {
        return target.extend(mixin);
    };
});

Can any one share some suggestion.

Thanks in advance.

Answer 1

You should use a wrapper for extending this plugin.

Documentation: https://developer.adobe.com/commerce/frontend-core/javascript/mixins#extend-js-object

Related question: https://magento.stackexchange.com/a/158072/53205

Magento example: https://github.com/magento/magento2/blob/821bcacdae33068457359f37d600af9cb654f763/app/code/Magento/SalesRule/view/frontend/web/js/model/shipping-save-processor-mixin.js#L13

define([
    'mage/utils/wrapper'
], function (wrapper) {
    'use strict';

    return function (stepNavigator) {
        stepNavigator.setHash = wrapper.wrapSuper(stepNavigator.setHash, function (hash) {
            this._super(hash);
            // add extended functionality here or modify method logic altogether
        });

        return stepNavigator;
    };
});

Older Magento 2 versions

Alan Storm has a good guide: http://alanstorm.com/the-curious-case-of-magento-2-mixins/ Magento example: https://github.com/magento/magento2/blob/2.1/app/code/Magento/CheckoutAgreements/view/frontend/web/js/model/place-order-mixin.js

define(['mage/utils/wrapper'],function (wrapper){
'use strict';

    return function (target) {
 
        var formAddressDataToQuoteAddress = wrapper.wrap(target.formAddressDataToQuoteAddress, function(super, formData){
            return super(formData);
        });

        target.formAddressDataToQuoteAddress = formAddressDataToQuoteAddress;

        return target;
    };
});

Answer 2

Just for the reference for some other people: Quisse is right. Problem with using extend with model/address-converter.js is that this file return an object. If it would return an UI component than code from the question would work because UI components have possibility to use extend method.