How does Vue 3 improve TypeScript support compared to Vue 2?

Vue 3's core is written in TypeScript, providing accurate types out of the box. Composition API functions like ref, reactive, and computed infer types automatically from their arguments, and defineProps/defineEmits support type-only generic syntax for full prop/emit type checking in <script setup lang="ts">.

Tooling improvements like Volar (the official VS Code extension) provide accurate template type-checking, autocompletion for props/emits/slots, and cross-file type inference — a significant step up from Vue 2, where TypeScript support for the Options API often required verbose helper functions like defineComponent with limited inference.