v-for for list rendering in Vue - Step-by-Step Execution

Concept Flow - v-for for list rendering

Start with array data

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Vue template reads v-for directive

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Loop over each item in array

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Create DOM element for each item

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Insert elements into parent container

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Render list on page

Vue reads the v-for directive, loops over the array, creates elements for each item, and renders them inside the parent container.

Execution Sample

Vue

<template>
  <ul>
    <li v-for="item in items" :key="item.id">{{ item.name }}</li>
  </ul>
</template>

<script setup>
const items = [{ id: 1, name: 'Apple' }, { id: 2, name: 'Banana' }]
</script>

This code loops over the items array and renders each item's name inside a list item.

Execution Table

Step	Action	Current Item	DOM Element Created	Parent Container
1	Start loop	N/A	N/A	<ul> (empty)</ul>
2	Process first item	{ id: 1, name: 'Apple' }	<li>Apple</li>	<ul><li>Apple</li></ul>
3	Process second item	{ id: 2, name: 'Banana' }	<li>Banana</li>	<ul><li>Apple</li><li>Banana</li></ul>
4	Loop ends	N/A	N/A	<ul><li>Apple</li><li>Banana</li></ul>

💡 All items processed, loop ends and list is fully rendered.

Variable Tracker

Variable	Start	After 1	After 2	Final
items	[{id:1,name:'Apple'},{id:2,name:'Banana'}]	Same	Same	Same
item	N/A	{id:1,name:'Apple'}	{id:2,name:'Banana'}	N/A

Key Moments - 2 Insights

Why do we need to use :key with v-for?

The :key helps Vue track each item uniquely during updates, so it can efficiently update only changed elements. See execution_table rows 2 and 3 where each item creates a separate <li>.

What happens if the array is empty?

If the array is empty, the loop does not run and no list items are created. The parent container remains empty, as shown in execution_table step 1 before looping starts.

Visual Quiz - 3 Questions

Look at the execution table, what is the DOM content inside <ul> after step 3?

A <li>Apple</li>

B <li>Apple</li><li>Banana</li>

C Empty <ul>

D <li>Banana</li>

💡 Hint

Check the 'Parent Container' column at step 3 in the execution_table.

At which step does the loop finish processing all items?

A Step 2

B Step 3

C Step 4

D Step 1

💡 Hint

Look at the 'Action' column for the step where the loop ends in the execution_table.

If the items array had 3 objects, how many <li> elements would be created?

A 3

B 2

C 1

D 0

💡 Hint

Refer to the pattern in execution_table rows 2 and 3 where each item creates one

.

Concept Snapshot

v-for directive loops over arrays or objects.
Syntax: v-for="item in items".
Use :key for unique identification.
Creates one DOM element per item.
Renders list inside parent container.
Efficient updates with keys.

Full Transcript

The v-for directive in Vue loops over an array or object to render a list of elements. Vue reads the v-for, then for each item in the array, it creates a DOM element, like a list item, and inserts it into the parent container. Using a unique :key helps Vue track each element for efficient updates. If the array is empty, no elements are created. This process repeats until all items are rendered, producing a visible list on the page.