Suggest an editImprove this articleRefine the answer for “How does v-if work?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**`v-if`** is a Vue directive for conditional rendering that adds or removes an element from the DOM depending on an expression. **Key point:** if the condition is true, the element is created and inserted into the DOM; if false, it is removed completely, along with the corresponding lifecycle hooks.Shown above the full answer for quick recall.Answer (EN)Image`v-if` is a Vue directive for **conditional rendering** that *adds or removes an element from the DOM* depending on an expression. In simpler terms: > **If the condition is true, the element is created and inserted into the DOM.** > **If it is false, the element is removed completely.** --- ## How `v-if` works Example: ```html <p v-if="isVisible">Hello!</p> ``` If `isVisible = true` → Vue creates the element If `isVisible = false` → the element is removed --- ## `v-if`, `v-else-if`, `v-else` ```html <div v-if="status === 'success'">Success</div> <div v-else-if="status === 'error'">Error</div> <div v-else>Unknown</div> ``` --- ## The lifecycle of `v-if` When the condition changes: - If it switches **to true**, Vue *creates a new DOM element* and runs all the hooks (mounted, updated, etc.). - If it switches **to false**, Vue *removes the element from the DOM*, calling the unmounted hooks. This matters at interviews. --- ## Important nuances ### 1. `v-if` **is used for rarely displayed elements** For example, modals, heavy lists, complex blocks. Because every time the element is created and destroyed → this is more costly. --- ### 2. `v-if` **cannot be used with** `v-for` **on the same element (Vue 3)** Not allowed: ```html <div v-for="item in items" v-if="item.visible"></div> ``` But allowed: ```html <template v-for="item in items"> <div v-if="item.visible">{{ item.name }}</div> </template> ``` Or filter the data beforehand. --- ### 3. **Grouping through** `<template>` ```html <template v-if="show"> <h1>Title</h1> <p>Text</p> </template> ``` `<template>` is not rendered into the DOM, only its contents are. --- ### 4. Differences from `v-show` | `v-if` | `v-show` | |---|---| | completely removes/creates the node | just hides it through `display: none` | | more expensive on frequent toggles | more expensive on first render | | suited for rarely displayed content | suited for frequent toggling | --- ## Example with animation (transition + v-if) Vue understands enter/leave transitions: ```html <transition> <p v-if="visible">Hello!</p> </transition> ``` When `visible` changes, Vue runs the CSS animation for appearing or disappearing.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.