[Vuejs]-CSS Show div, detect if end of screen

Suggest to use Floating-ui (well known as Poper)

Floating UI is a low-level library for positioning "floating" elements…intelligently keeping them in view

It’s been using widely and cover a lot of edge cases you might encounter when try to create dropdown yourself

You can try with references here

• creating-vue-component-dropdown-with-popper-js
• floating-vue/dropdown