Q: What is v-html and what is the risk of using it?

**Target Audience:** Beginners who have seen v-html in a codebase, or are tempted to use it. Basic HTML assumed; no security background needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered HTML was produced by mounting the example on Vue 3.5.44 in jsdom and with renderToString . Because jsdom does not load images (so an onerror payload can never fire there), the attack its

Question 1

What is Vue.js and what are its core features?

Accepted Answer

**Target Audience:** Complete beginners preparing for a first Vue interview. Assumes you know a little HTML and JavaScript, nothing about Vue or any other framework. **Difficulty:** Easy > **How to read this doc:** Every idea is explained in plain language first, then tagged with 📌 Interview term: so you also learn the exact words an interviewer listens for. The outputs in sections 5 and 6 were produced by actually compiling and running the code on Vue 3.5.44, the current stable r

Question 2

What is v-html and what is the risk of using it?

Accepted Answer

**Target Audience:** Beginners who have seen v-html in a codebase, or are tempted to use it. Basic HTML assumed; no security background needed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered HTML was produced by mounting the example on Vue 3.5.44 in jsdom and with renderToString. Because jsdom does not load images (so an onerror payload can never fire there), the attack its

Question 3

What are Vue directives? Give common examples.

Accepted Answer

**Target Audience:** Beginners who can read a basic Vue template and want to understand every v- attribute they see. Basic HTML and JavaScript assumed. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The rendered output, the compiled render function and the warnings below come from compiling and mounting the example on Vue 3.5.44, not from memory. ## 1. Why This Even Matters — A Story First Imagine a theatre sc

Question 4

What is Vue template syntax (interpolation, directives, expressions)?

Accepted Answer

**Target Audience:** Beginners who know basic HTML and JavaScript and are reading Vue templates for the first time. **Difficulty:** Easy > **How to read this doc:** Plain language first, then 📌 Interview term: callouts with the precise vocabulary. Every rendered output, compiled render function, warning and error message below was produced by running the code on Vue 3.5.44 (@vue/compiler-dom for compiler output, the repo verifier for mounted components). ## 1. Why Th

Question 5

How do you create a custom directive in Vue?

Accepted Answer

**Target Audience:** Vue developers who need low-level DOM behaviour they can reuse across templates. **Difficulty:** Medium > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. Every log line and warning below was printed on Vue 3.5.44 by mounting the SFCs in jsdom with the repo verifier (dev build), and the SSR output by renderToString from @vue/server-renderer. The typed example was checked with TypeScript 5 in strict mode

Question 6

What are v-once and v-memo?

Accepted Answer

**Target Audience:** Vue developers optimising rendering, and anyone asked how Vue templates compile. **Difficulty:** Hard > **How to read this doc:** Plain language first, then 📌 Interview term: callouts. The compiled render functions below were printed by compile() from @vue/compiler-dom and @vue/compiler-ssr 3.5.44 (the import lines are trimmed); render counts and behaviour come from mounting the SFCs in jsdom with the repo verifier. For t

Question 7

How does the Vue compiler optimize templates (static hoisting, patch flags, block tree)?

Accepted Answer

**Target Audience:** Vue developers who know the virtual DOM exists and want to explain how Vue makes it cheap. No compiler background needed. **Difficulty:** Hard > **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 compiled snippet is real output of @vue/compiler-sfc 3.5.44 compileTemplate() (production mode), with one comparison against

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