Conditional rendering is a term to describe the ability to render different user interface (UI) markup depending on if a condition is true or false.
Conditional Rendering can be implemented in Vue using the directives below
The "v-if" directive can used to conditionally render an element including other elements that may be within it. The block will only be rendered if the directive’s expression returns a truthy value.
<h1 v-if="showGreeting">Welcome Home!</h1>
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?
You can also add conditional rendering to a group of elements by wrapping them in a "" element as shown below
<template v-if="Chores"> 🙃 <h1>Chores</h1> <ul> <li>Wash the cat</li> <l1>Do the dishes</li> <ul> </template>
"" element serves as an invisible wrapper and will not be displayed in the final rendered result.
The "v-else" directive can only be used immediately after the "v-if" directive. They follow the pattern of a typical if-else statement.
The content within the "v-else" element will be rendered if the condition set in the "v-if" element is not met.
<template v-if="Chores"> 🙃 <h1>Chores</h1> <ul> <li>Wash the cat</li> <l1>Do the dishes</li> <ul> </template> <h1 v-else> Watch television</h1> 😀
The "v-else" element gives you only one other option to render if "v-if" element's condition is not met.
"v-else-if" serves as an else-if block for "v-if". It can also be chained multiple times so it enable you to have more than one option to render.
<template v-if="Chores"> 🙃 <h1>Chores</h1> <ul> <li>Wash the cat</li> <l1>Do the dishes</li> <ul> </template> <h1 v-else-if="Homework"> Do homework</h1> <h1 v-else> Watch television</h1> 😀
"v-show" is very similar to "v-if"
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" does not work in the "template" element nor does it work with "v-else".
"v-if" has higher toggle costs while "v-show" has higher initial render costs. So use "v-show" if you need to toggle something very often, and prefer "v-if" if the condition is unlikely to change at runtime.
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