- initial widget
Magento_Theme/js/view/breadcrumbs(vendor/magento/module-theme/view/frontend/web/js/view/breadcrumbs.js) - native mixin that extends this widget:
Magento_Catalog/js/product/breadcrumbs(vendor/magento/module-catalog/view/frontend/web/js/product/breadcrumbs.js)
Extend methods of the mixin Magento_Catalog/js/product/breadcrumbs
- Declare your mixin in custom theme
app/design/frontend/[Vendor]/[theme]/Magento_Catalog/requirejs-config.jsfile and associate it with the initial widget