How to override Magento 2 js using Mixins? A Magento 2 RequireJS “mixins” allows you to programmatically listen for the initial instantiation of any RequireJS, How do mixins in Magento 2 work? First, create requirejs-config.js Magento_Checkout/js/model/quote js file you want to rewrite.PackageName_ModuleName/js/plugin-quote target file.plugin-quote.js You can’t access the private variable from Magento_Checkout/js/model/quote. What is a private variable If your source file is returned $.mage.[widgetName] ex : Magento_Catalog/js/price-box.js Your destination file must return $.mage.[widgetName]