Q: What are common reactivity caveats in Vue?

**Target Audience:** Developers who have shipped Vue 3 code and want to explain, not just recognise, the reactivity bugs that show up in code review. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every symptom and every warning or error message below was produced on Vue 3.5.44: reactivity probes with node , the compiler check with @vue/compiler-sfc , and the components compiled and clicked in jsdom.

Question 1

How do you optimize performance in a Vue app?

Accepted Answer

**Target Audience:** Vue developers who have shipped an app and now need a method for making it faster. Assumes the Composition API basics. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every number here was measured for this answer on Vue 3.5.44: the re-render counts by mounting the runnable example in jsdom with scripts/verify-vue-exa

Question 2

When should you use readonly, markRaw, and toRaw in Vue reactivity?

Accepted Answer

**Target Audience:** Vue developers designing composables and stores, or integrating non-Vue libraries. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Warnings, outputs and timings below come from running code on Vue 3.5.44 (Node 22, and jsdom for the component); timings are from one sandbox machine. This page is the **decision guide**. The mechanics are covered by two sibling questions: [What does readonly do in Vue's rea

Question 3

How do dynamic components work?

Accepted Answer

**Target Audience:** Developers who know basic Vue templates and components and want to understand runtime component switching. **Difficulty:** Medium > **How to read this doc:** Ideas are explained in plain language first, then tagged with 📌 Interview term: so you also learn the words an interviewer listens for. Every output block in this doc was produced by compiling and running the code on Vue 3.5.44, either with the repo's verify-vue-example.mjs harness (compile t

Question 4

What do markRaw and toRaw do?

Accepted Answer

**Target Audience:** Vue developers integrating third-party objects or debugging identity bugs in reactive state. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every value and error message below was printed by running the code on Vue 3.5.44 in Node 22, or by mounting the SFC in jsdom with the repo verifier. This page explains **how** markRaw and toRaw work. For **when** to choose them, alongside <

Question 5

What are common reactivity caveats in Vue?

Accepted Answer

**Target Audience:** Developers who have shipped Vue 3 code and want to explain, not just recognise, the reactivity bugs that show up in code review. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every symptom and every warning or error message below was produced on Vue 3.5.44: reactivity probes with node, the compiler check with @vue/compiler-sfc, and the components compiled and clicked in jsdom.

VUE.JSDECODED.

Medium

How do you optimize performance in a Vue app?

When should you use readonly, markRaw, and toRaw in Vue reactivity?

How do dynamic components work?

Hard

What do markRaw and toRaw do?

What are common reactivity caveats in Vue?