if(this.$route.params.topic){ return this.$route.params.topic }else{ return "shopping"; }

This code is a method in a Vue.js component that returns either the value of the "topic" parameter in the current route, or the string "shopping" if the "topic" parameter is not present.

The "this.$route.params" object contains all the parameters in the current route, including the "topic" parameter if it was specified.

If the "topic" parameter is present, the method returns its value. Otherwise, it returns the default value of "shopping".

This code is useful for building dynamic components that display different content based on the current route, such as a blog post page that displays different posts based on the "slug" parameter in the URL.