v-if
The directive v-if is used to conditionally render a block. The block will only be rendered if the directive’s expression returns a truthy value.
<h1 v-if="awesome">Vue is awesome!</h1>
It is also possible to add an “else block” with v-else:
<h1 v-if="awesome">Vue is awesome!</h1> <h1 v-else>No</h1>
Conditional Groups with v-if on <template>
Because v-if is a directive, it has to be attached to a single element. But what if we want to toggle more than one element? In this case we can use v-if on a <template> element, which serves as an invisible wrapper. The final rendered result will not include the <template> element.
<template v-if="ok"> <h1>Title</h1> <p>Paragraph 1</p> <p>Paragraph 2</p> </template>
v-else
You can use the v-else directive to indicate an “else block” for v-if:
<div v-if="Math.random() > 0.5"> Now you see me </div> <div v-else> Now you don't </div>
A v-else element must immediately follow a v-if or a v-else-if element – otherwise it will not be recognized.
v-else-if
The v-else-if, as the name suggests, serves as an “else if block” for v-if. It can also be chained multiple times:
<div v-if="type === 'A'"> A </div> <div v-else-if="type === 'B'"> B </div> <div v-else-if="type === 'C'"> C </div> <div v-else> Not A nor B nor C </div>
Similar to v-else, a v-else-if element must immediately follow a v-if or a v-else-if element.
v-show
Another option for conditionally displaying an element is the v-show directive. The usage is largely the same:
<h1 v-show="ok">Hello!</h1>
The difference is that an element with v-show will always be rendered and remain in the DOM; v-show only toggles the display CSS property of the element.
v-show doesn’t support the <template> element, nor does it work with v-else.
v-if vs v-show
v-if is “real” conditional rendering because it ensures that event listeners and child components inside the conditional block are properly destroyed and re-created during toggles.
v-if is also lazy: if the condition is false on initial render, it will not do anything – the conditional block won’t be rendered until the condition becomes true for the first time.
In comparison, v-show is much simpler – the element is always rendered regardless of initial condition, with CSS-based toggling.
Generally speaking, v-if has higher toggle costs while v-show has higher initial render costs. So prefer v-show if you need to toggle something very often, and prefer v-if if the condition is unlikely to change at runtime.
<p v-show="show">v-show</p>
<p v-if="show">v-if</p>
<p v-show="!show">not v-show</p>
<p v-if="!show">not v-if</p>
show = false
Render result:
<p style="display: none;">v-show</p> <!--v-if--> <p>not v-show</p> <p>not v-if</p>
v-if with v-for
Using v-if and v-for together is not recommended. See the style guide for further information.
When used together with v-if, v-for has a higher priority than v-if. See the list rendering guide for details.
