Hello Trailblazers!
In this post, we will see how to control the visibility of elements in the LWC template using the LWC conditional directives.
Previously we used if:true
and if:false
directives
to conditionally show or hide the elements on the component. But from the
Spring 2023 release, we will use a new lwc:if
,
lwc:elseif
, and lwc:else
directives.
The new conditional directives are more powerful and flexible than the legacy directives. They allow you to create complex conditional statements, and they also provide better performance.
The lwc:if
directive
The lwc:if
directive is used to render HTML if a condition is
true. The condition can be a property, the result of an expression, or even
a function call.
Example:
<template> <lightning-card title="Conditional Rendering"> <div class="slds-m-around_medium"> <template lwc:if={condition}> </template> </div> </lightning-card> </template>
The lwc:elseif
and lwc:else
directives
The lwc:elseif
and lwc:else
directives are used
to create more complex conditional statements.
The lwc:elseif
directive is used to render HTML if a
condition is true, but only if the previous conditions have been evaluated
as false.
The lwc:else
directive is used to render HTML if all of the
previous conditions have been evaluated to be false.
For example:
<template> <lightning-card title="Conditional Rendering"> <div class="slds-m-around_medium"> <template lwc:if={condition1}> </template> <template lwc:elseif={condition2}> </template> <template lwc:else> </template> </div> </lightning-card> </template>
Best practices for using lwc:if
,
lwc:elseif
and lwc:else
directives
-
Use the
lwc:if
,lwc:elseif
, andlwc:else
directives instead of the legacyif:true
andif:false
directives. - Keep your conditional statements as simple as possible. If you need to create a complex conditional statement, consider using a getter in your JavaScript class.
- Use comments to document your conditional statements, so that it is easy to understand what they are doing.
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