v-for with v-if precedence in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does v-for do in Vue?

v-for repeats a block of HTML for each item in a list or object. It helps show many similar elements easily.

beginner

What is the role of v-if in Vue?

v-if conditionally shows or hides an element based on a true or false value.

intermediate

In Vue, which has higher priority: v-for or v-if when used on the same element?

v-for runs first, then v-if checks each item. So, Vue loops over all items, then decides which to show.

intermediate

Why should you avoid putting v-if and v-for on the same element?

Because Vue loops over all items first, then filters with v-if. This can hurt performance if the list is large.

intermediate

How can you improve performance when you want to filter items in a list before looping in Vue?

Filter the list in a computed property or method first, then use v-for on the filtered list without v-if.

What happens first when Vue processes an element with both v-for and v-if?

A Vue throws an error

B <code>v-if</code> runs first, then <code>v-for</code>

C They run simultaneously

D <code>v-for</code> runs first, then <code>v-if</code>

Vue always processes v-for before v-if on the same element.

Why is using v-if inside v-for on the same element sometimes bad?

A It causes syntax errors

B It can slow down rendering for large lists

C It hides all elements

D It disables reactivity

Because Vue loops over all items before filtering, it can hurt performance on big lists.

What is a better way to conditionally show items in a list in Vue?

A Use <code>v-if</code> only without <code>v-for</code>

B Use <code>v-for</code> only without filtering

C Filter the list first, then use <code>v-for</code> without <code>v-if</code>

D Use <code>v-show</code> inside <code>v-for</code>

Filtering the list before looping is more efficient and clearer.

If you want to show only items with active === true, where should you put the condition?

A In a computed property that returns only active items

B Directly in <code>v-if</code> on the <code>v-for</code> element

C In a method called inside the template

D In a watcher

Computed properties efficiently prepare filtered lists for rendering.

What does Vue do if you put v-if and v-for on different elements?

A Processes <code>v-if</code> first on the parent, then loops with <code>v-for</code>

B Processes <code>v-for</code> first on the child, then <code>v-if</code>

C Throws an error

D Ignores <code>v-if</code>

When separated, v-if on the parent runs before v-for on the child.

Explain how Vue handles v-for and v-if when used together on the same element. Why does this matter?

Think about the order Vue processes directives and how that affects rendering speed.

Describe a better approach to conditionally render items from a list in Vue instead of using v-if inside v-for.

Consider how to prepare data before rendering.