`defineExpose` trong `<script setup>` là gì?

Trong <script setup>, component instance mặc định không expose properties ra ngoài (không access được qua template ref). defineExpose cho phép explicitly expose các methods/properties để parent gọi qua ref.

Ví dụ: defineExpose({ focus, reset }) — parent gọi childRef.value.focus(). Dùng khi cần imperative control (focus, scroll, reset form). Lưu ý: không expose quá nhiều — tránh biến component thành "god object", ưu tiên event-based communication.

In <script setup>, component instances do not expose properties by default (not accessible via template ref). defineExpose explicitly exposes methods/properties for parent access via ref.

Example: defineExpose({ focus, reset }) — parent calls childRef.value.focus(). Use for imperative control (focus, scroll, form reset). Pitfall: do not over-expose — avoid turning components into "god objects"; prefer event-based communication.