In the era of SPA and the JAMstack, there has always been a separation of concern between the APIs and front-end development. Almost all JavaScript projects that can be found out in the wild interact with a web service or API and either use it for authentications or getting user-related data. So, whenever you’re working on a project and the necessary API still hasn’t been implemented by the back-end team or you need to quickly test a feature, you have some of the following options:

https://www.smashingmagazine.com/2020/02/api-mocking-mirage-vue-javascript/