Increasing the speed and smoothness of an application requires performance tuning. To aid in this, Angular, a well-liked framework for creating online applications, has introduced the @defer directive. Both load times and user experience are enhanced. We'll explain the @defer directive, its operation, and how you can use it to improve your Angular apps in this blog post.

@defer: What is it?

Using an Angular condition, the @defer directive allows you to load specific portions of a template only when needed. This can improve the efficiency of your program by only rendering components when required. For instance, it can load and display material only after the user presses a button or until a certain portion of the screen is visible. In this manner, your software loads faster and more effectively because it just loads what is needed.

Syntax
@defer () {
} @placeholder () {
} @loading () {
} @error {
}

@defer Directive
This is used to delay the loading of a template fragment until certain conditions are met.
on <trigger>: Specifies an event that triggers the deferred loading. Here is one simple example of on viewport trigger

@defer (on viewport) {
  <component />
}

(on viewport) specifies that the deferred rendering should happen when the element comes into the viewport.

when <condition>: Defines the condition that needs to be true before the template is loaded.
prefetch on <trigger>: Optionally, you can prefetch the content based on a trigger.
prefetch when <condition>: Optionally, you can prefetch the content when a certain condition is true.

@placeholder Directive
This defines what should be shown while the deferred content is being loaded.

@loading Directive
This defines the content to be shown while the deferred content is actually loading.

@error Directive
This defines what should be shown if there's an error during the loading process.

In short, this syntax lets you control when different parts of your Angular template appear and what to show while you’re waiting, depending on different conditions and triggers.

Benefits of Using @defer directive

• Faster Loading: By delaying less important content, your app loads quicker and feels smoother to use.
• Better User Experience: Users see the key parts of your app right away, while the less important stuff loads in the background, so the app stays responsive.
• Efficient Use of Resources: By waiting to display parts of your app that aren’t needed right away, you free up your browser’s resources, making everything run more smoothly.

Summary
The @defer directive in Angular helps make your app run better and faster. It allows you to delay loading some parts of your app until they're really needed. This way, your app stays quick and responsive, even if it has a lot of data or complex tasks. Using @defer can make your app perform better and provide a smoother experience for users.

Please let me know in the comments area if you have any questions.