Deferrable Views - New Feature in Angular 17

Summary

This video script unveils the powerful 'defer views' feature introduced in Angular 17, aiming to enhance bundle size reduction and user experience for Angular applications. The narrator, M Mki, an Angular tutorial creator, delves into the intricacies of this feature, demonstrating how it streamlines lazy loading of components based on various triggers like viewport visibility, button clicks, and custom logic. The video showcases techniques for improving perceived performance, such as placeholders, loading indicators, and error handling. It also explores advanced capabilities like prefetching components in the background for instant rendering. Overall, the script promises an in-depth exploration of this cutting-edge Angular feature, positioning it as a game-changer for optimizing Angular apps.

Takeaways

• 😎 Angular 17 introduces a new 'defer views' feature that reduces bundle size and improves user experience for lazy-loaded components.
• 🔑 The 'defer' block is used to wrap heavy components that need to be lazy-loaded, simplifying the process compared to previous approaches.
• ⏱️ 'defer views' provides placeholders, error handling, and loading templates to improve the user experience during lazy loading.
• 🎯 Built-in triggers like 'timer', 'viewport', and 'idle' allow controlling when lazy components are loaded and activated based on various conditions.
• 🔭 Custom triggers can be created using the 'when' keyword to define specific logic for loading and activating lazy components.
• 🚀 The 'prefetch' keyword enables preloading lazy components in the background, further improving the user experience.
• 🧩 Custom preloading logic can be implemented by providing a Boolean value to the 'prefetch' keyword.
• 📐 The 'defer views' feature provides a powerful and declarative way to manage lazy loading in Angular applications.
• 🌐 The new feature makes Angular one of the frameworks with the most powerful lazy loading mechanisms on the market.
• 📢 The video encourages viewers to share, subscribe, and check out the author's video courses to level up their Angular skills.

Q & A

What is the new feature introduced in Angular 17?

The new feature introduced in Angular 17 is called 'defer views'. It aims to reduce bundle size, improve user experience, and provide a more efficient way to lazy-load components in Angular applications.

How does the 'defer views' feature differ from the traditional router-based lazy loading?

Unlike router-based lazy loading, which loads components based on the Angular router state, 'defer views' allows lazy loading of components based on certain component states or events, providing more flexibility and control over the loading process.

How does the 'defer views' feature simplify the lazy loading process compared to previous versions of Angular?

The 'defer views' feature simplifies lazy loading by providing a declarative syntax using the 'deferView' block, which wraps the lazy component. This eliminates the need for complex code involving dynamic imports, dynamic component creation, and other low-level Angular APIs, making the process more straightforward and readable.

What are some of the additional features provided by 'defer views' beyond simple lazy loading?

The 'defer views' feature offers additional functionality such as placeholders, error handling, loading indicators, and various triggers (e.g., timer, viewport, custom triggers) to control when and how the lazy component is loaded and activated.

How does the 'placeholder' block in 'defer views' help improve user experience?

The 'placeholder' block in 'defer views' allows you to show a placeholder content before the lazy component is loaded and activated. This helps prevent layout shifts or flickering and provides visual feedback to the user that something is loading.

What is the difference between the 'loading' and 'placeholder' blocks in 'defer views'?

The 'loading' block is used to show content during the phase when the lazy component's JavaScript chunk is being loaded, while the 'placeholder' block is shown before the loading phase starts, providing an initial placeholder until the actual content appears.

What are 'defer view triggers', and how do they help control the lazy loading process?

Defer view triggers are instructions that determine when the lazy chunk should be loaded and activated for the 'defer views' block. Angular provides built-in triggers like 'timer', 'viewport', and the ability to create custom triggers based on specific conditions or events.

What is the purpose of the 'prefetch' keyword in 'defer views'?

The 'prefetch' keyword in 'defer views' allows you to preload the lazy component's JavaScript chunk in the background before it's actually needed, improving the user experience by instantly rendering the component when the trigger condition is met.

Can you provide an example of a custom trigger for 'defer views'?

Yes, a custom trigger can be created using the 'when' keyword followed by a boolean value. For example, 'when' can be set to a boolean property that changes based on a button click, allowing the lazy component to be loaded and activated when the button is clicked.

How does the 'defer views' feature compare to similar lazy loading mechanisms in other frameworks?

According to the speaker, the 'defer views' feature in Angular 17 makes Angular one of the frameworks with the most powerful lazy loading mechanisms on the market, providing a comprehensive set of tools and features for optimizing bundle size and improving user experience.