Javascript

Making Seamless Page Transitions with the View Transitions API

Published Aug 2, 2024

Updated Aug 2, 2024

4 min read

Make Seamless Page Transitions using the View Transitions API

Traditionally web applications have always had a less polished experience, both functionally and visually speaking, compared to native applications on mobile and other platforms. This has been improving over the years with the introduction of new web APIs and standards.

One such new API that bridges that gap is the View Transitions API.

What is the View Transitions API?

The View Transitions API is a new browser feature that allows developers to more easily create animated transitions between pages and views, similar to how mobile apps have transitions when navigating between pages.

Adding view transitions to your application can reduce the cognitive load on your users and make the experience feel less inconsistent. One great thing about view transitions is that they can be used by both SPAs (single-page applications) and MPAs (multi-page applications) alike!

Using the View Transitions API for SPAs

Let’s see how we can use view transitions ourselves. We will use examples adapted from demos created by the wonderful Jake Archibald and Bramus. There are some alterations to a few of the examples to make them work with the newest version of the View Transitions API, but otherwise, they’re mostly the same.

The process of getting view transitions working for SPAs is as simple as calling document.startViewTransition right before starting navigation and replacing your page’s content immediately after that. You need to make this call in your router or in an event listener that triggers your page navigation.

The following is an example of how you can hook into page navigation in a vanilla JavaScript application. This example uses the Navigation API if it’s available. As of the time of writing this article only Chromium-based browsers support the Navigation API, but there is a fallback to using a click listener on link elements so that this works with Firefox and Safari.

export async function onLinkNavigate(callback) {
  // Fallback to intercepting click events on <a> tags if the
  // Navigation API is not supported by the browser.
  //
  // For modern JavaScript frameworks with client-side routing
  // you would want to hook into the router instead as <a> tags
  // may not be the only way pages are navigated to.
  if (!self.navigation) {
    document.addEventListener('click', (event) => {
      const link = event.target.closest('a');
      if (!link) return;

      event.preventDefault();

      const toUrl = new URL(link.href);

      callback({
        toPath: toUrl.pathname,
        fromPath: location.pathname,
        isBack: false,
      });

      history.pushState({}, null, toUrl.pathname);
    });
    return;
  }

  // Use the Navigation API if it is available.
  navigation.addEventListener('navigate', (event) => {
    const toUrl = new URL(event.destination.url);

    // Do not intercept the event if we're navigating to
    // URL on another domain origin.
    if (location.origin !== toUrl.origin) return;

    const fromPath = location.pathname;
    const isBack = isBackNavigation(event);

    event.intercept({
      async handler() {
        if (event.info === 'ignore') return;

        await callback({
          toPath: toUrl.pathname,
          fromPath,
          isBack,
        });
      },
    });
  });
}

If you’re using a framework, then there’s probably a better way to do this specific to that framework than by using this contrived example. For example, if you are implementing usage of this API with a Next application, you may opt for something like next-view-transitions.

For this article, we’re going to focus on the way this is done in vanilla JavaScript so that the fundamentals of using the API are understood. Knowing how it’s implemented in vanilla JavaScript should give you enough understanding to implement this in the framework of your choice if there isn’t already a library that does it for you.

Now we have a way to know when a navigation is being requested. Using the above utility function we can start the animation and replace our content as follows:

onLinkNavigate(async ({ toPath }) => {
  const content = await getMyPageContentSomehow(toPath);

  startViewTransition(() => {
    document.body.innerHTML = content;
  });
});

function startViewTransition(callback) {
  if (!document.startViewTransition) {
    callback();
    return;
  }

  document.startViewTransition(callback);
}

getMyPageContentSomehow can be any function that returns HTML. How that is implemented will depend on your application and framework of choice.

If you want to run these examples on your machine, the demo repository has instructions in its README. In essence, it’s as simple as hosting an HTTP server at the root of the project and visiting localhost. No fancy build system is required!

By default, a fade is done that only lasts for a moment. The animation that happens can be configured using CSS with the ::view-transition-group pseudo-element on the element you want to animate, which in our case is the entire page, and we pass in root.

::view-transition-group(root) {
  animation-duration: 5s;
}

Given that the animation properties are used, you have much control over what kind of animation to do. You can change the duration and the interpolation, add keyframes and gradients, and even add image masks. You can learn more about the animation properties in CSS on MDN.

Using the View Transitions API for MPAs

As mentioned, view transitions also work for MPAs with no client-side routing. Setting up view transitions for MPAs is much easier than for SPAs. All you have to do is include the CSS rule on all pages where you want the animations.

@view-transition {
    navigation: auto;
}

Of course, like how it works with SPAs, you can customize the animations to your heart’s content using the view transition pseudo-elements.

Conclusion

I hope this article helped you understand the fundamentals of using the View Transitions API. Now that most browsers support it and it’s not too difficult to add it to existing applications, it is a great time to learn how to use it.

You can view a full list of examples here (made by Jake Archibald and Bramus) if you want to see how advanced the animations can get. I like the Star Wars ones especially. The README explains how to get all the examples up and running (a total of 43!).

This Dot is a consultancy dedicated to guiding companies through their modernization and digital transformation journeys. Specializing in replatforming, modernizing, and launching new initiatives, we stand out by taking true ownership of your engineering projects.

We love helping teams with projects that have missed their deadlines or helping keep your strategic digital initiatives on course. Check out our case studies and our clients that trust us with their engineering.

About the author(s)

Jamie Kuppens
I’m a software engineer with an interest in web development and some more esoteric things like emulator development.
@Reshurum @Reshurum

Angular 18 Announced: Zoneless Change Detection and More

Angular 18 Announced: Zoneless Change Detection and More Angular 18 has officially landed, and yet again, the Angular team has proven that they are listening to the community and are committed to continuing the framework's renaissance. The release polishes existing features, addresses common developer requests, and introduces experimental zoneless change detection. Let's examine the major updates and enhancements that Angular 18 offers. 1. Zoneless Angular One of the most exciting features of Angular 18 is the introduction of experimental support for zoneless change detection. Historically, Zone.js has been responsible for triggering Angular's change detection. However, this approach has downsides, especially regarding performance and debugging complexity. The Angular team has been working towards making Zone.js optional, and Angular 18 marks a significant milestone in this journey. Key Features of Zoneless Angular 1. Hybrid Change Detection: In Angular 18, a new hybrid change detection mode is enabled by default. This mode allows Angular to listen to changes from signals and other notifications regarding changes that occur either inside an Angular zone or not. That effectively means you can write (library) code that works regardless of whether Zone.js is being used, paving the way to fully zoneless apps without compromising backward compatibility. For new applications, Angular enables zone coalescing by default, which removes the number of change detection cycles and improves performance. For existing applications, you can enable zone coalescing by configuring your NgZone provider in bootstrapApplication: ` 2. Experimental API for Zoneless Mode: Angular 18 introduces an experimental API to disable Zone.js entirely. This API allows developers to run applications in a fully zoneless mode, paving the way for improved performance and simpler debugging. The zoneless change detection requires an entirely new scheduler which relies on notifications from the Angular core APIs, such as ChangeDetectorRef.markForCheck (called automatically by the AsyncPipe), ComponentRef.setInput, signal updates, host listener updates, or attaching a view that was marked dirty. 3. Improved Composability and Interoperability: Zoneless change detection enhances composability for micro-frontends and interoperability with other frameworks. It also offers faster initial render and runtime, smaller bundle sizes, more readable stack traces, and simpler debugging. How to Try Zoneless Angular To experiment with zoneless change detection, you can add the provideExperimentalZonelessChangeDetection provider to your application bootstrap: ` After adding the provider, remove Zone.js from your polyfills in angular.json. You can read more about the experimental zoneless change detection in the official documentation. By the way, angular.dev is now considered the official home for Angular developers! 2. Server-side Rendering and Hydration Enhancements A feature I'm particularly excited about is the improvements to Angular's server-side rendering (SSR) and hydration in terms of developer experience and debugging: 1. Enhanced DevTools Support: Angular DevTools now includes overlays and detailed error breakdowns to help visualize and debug hydration issues directly in the browser. This refreshing focus on developer experience shows that the Angular team wants to make the framework more approachable and user-friendly. 2. Hydration Support for Angular Material: All Angular Material components now support client hydration and are no longer skipped, which enhances performance and user experience. 3. Event Replay: Available in developer preview, event replay captures user interactions during SSR and replays them once the application is hydrated, ensuring a seamless user experience before complete hydration. It is powered by the same library as Google Search. 4. i18n Hydration Support: Up to v17, Angular skipped hydration for components with i18n blocks. From v18, hydration support for i18n blocks is in developer preview, allowing developers to use client hydration in internationalized applications. 3. Stable Material Design 3 After introducing experimental support for Material Design 3 in Angular 17, Angular 18 now includes stable support. The key features of Material Design 3 in Angular 18 include: 1. Simplified Theme Styles: Based on CSS variables, the new theming styles offer more granular customization and a flexible API for applying color variants to components. 2. Theming Generation Schematics: Using the Ng CLI, you can generate Material 3 themes. 3. Sass APIs: New Sass APIs allow developers to read colors, typography, and other properties from the Material 3 theme, making it easier to create custom components. How to use Material Design 3 in Angular 18 To use Material Design 3 in Angular 18, you can define a theme in your application's styles.scss file using the mat.defineTheme function: ` Or generate a Material 3 theme using the Ng CLI: ` You can then apply the theme to your application using the mat.theme mixin: ` Head to the official guide for a more detailed guide. You'll also notice they have refreshed the docs with the new themes and further documentation. 4. Signal-Based APIs The path to fully signal-based components includes new signal inputs, model inputs, and signal query APIs. We already wrote about them as they were in developer-preview in v17, but they have been further refined in v18. These APIs offer a type-safe, reactive way to manage state changes and interactions within components: 1. Signal Input API: Signal inputs allow values to be bound from parent to child components. Those values are exposed using a signal and can change during the component's life cycle. 2. Model Input API: Model inputs are a special input type that enables a component to propagate new values back to the parent component. That allows developers to keep the parent component in sync with the child component with two-way binding. 3. Signal Query API: This was a particularly requested feature from the community. The signal query APIs work the same way as ViewChild and ContentChild under the hood, but they return signals, providing more predictable timing and type safety. 5. Fallback Content For ng-content A very requested feature from the community, Angular 18 introduces a new ng-content directive that allows developers to define fallback content when no content is projected into a component. This feature is particularly useful for creating reusable components with default content. Here's an example of using the new ng-content directive. Using the following component ` like this ` will render Howdy World. 6. Other Improvements In addition to the major updates mentioned above, Angular 18 also includes several other improvements and updates: 1. TypeScript 5.4: Angular 18 now supports TypeScript 5.4, which lets you take advantage of new features such as preserved narrowing in closures following last assignments. 2. Global Observable in Angular Forms: Angular 18 introduces a global events observable in Angular forms, which allows you to track all changes around any abstract control and its children, including the touched or dirty in a single observable. Here's an example of how you can use the global observable: ` 3. Stable Deferrable views: Deferrable views are now stable in Angular 18. 4. Stable Control Flow: The built-in control flow is now stable in Angular 18! It is more performant than its predecessor. It also received improved type checking, including guardrails for certain performance-related anti-patterns. 5. Route Redirects as Functions: For added flexibility in managing redirects, Angular v18 now lets you use a function for redirectTo that returns a string, which allows you to create more sophisticated redirection logic based on runtime conditions. For example: ` Conclusion Angular 18 is a significant release that brings many new features, enhancements, and experimental APIs to the Angular ecosystem. The introduction of zoneless change detection, improvements to server-side rendering and hydration, stable Material Design 3 support, signal-based APIs, and fallback content for ng-content are just a few of the highlights of this release. The Angular team has again demonstrated its commitment to improving the framework's developer experience, performance, and flexibility. It also demonstrated a clear vision for Angular's future. If you're curious about what's next, you can check out the Angular roadmap....

May 29, 2024

3 mins

AngularJavaScript

Exploring Angular Forms: A New Alternative with Signals

Exploring Angular Forms: A New Alternative with Signals In the world of Angular, forms are essential for user interaction, whether you're crafting a simple login page or a more complex user profile interface. Angular traditionally offers two primary approaches: template-driven forms and reactive forms. In my previous series on Angular Reactive Forms, I explored how to harness reactive forms' power to manage complex logic, create dynamic forms, and build custom form controls. A new tool for managing reactivity - signals - has been introduced in version 16 of Angular and has been the focus of Angular maintainers ever since, becoming stable with version 17. Signals allow you to handle state changes declaratively, offering an exciting alternative that combines the simplicity of template-driven forms with the robust reactivity of reactive forms. This article will examine how signals can add reactivity to both simple and complex forms in Angular. Recap: Angular Forms Approaches Before diving into the topic of enhancing template-driven forms with signals, let’s quickly recap Angular's traditional forms approaches: 1. Template-Driven Forms: Defined directly in the HTML template using directives like ngModel, these forms are easy to set up and are ideal for simple forms. However, they may not provide the fine-grained control required for more complex scenarios. Here's a minimal example of a template-driven form: ` ` 2. Reactive Forms: Managed programmatically in the component class using Angular's FormGroup, FormControl, and FormArray classes; reactive forms offer granular control over form state and validation. This approach is well-suited for complex forms, as my previous articles on Angular Reactive Forms discussed. And here's a minimal example of a reactive form: ` ` Introducing Signals as a New Way to Handle Form Reactivity With the release of Angular 16, signals have emerged as a new way to manage reactivity. Signals provide a declarative approach to state management, making your code more predictable and easier to understand. When applied to forms, signals can enhance the simplicity of template-driven forms while offering the reactivity and control typically associated with reactive forms. Let’s explore how signals can be used in both simple and complex form scenarios. Example 1: A Simple Template-Driven Form with Signals Consider a basic login form. Typically, this would be implemented using template-driven forms like this: ` ` This approach works well for simple forms, but by introducing signals, we can keep the simplicity while adding reactive capabilities: ` ` In this example, the form fields are defined as signals, allowing for reactive updates whenever the form state changes. The formValue signal provides a computed value that reflects the current state of the form. This approach offers a more declarative way to manage form state and reactivity, combining the simplicity of template-driven forms with the power of signals. You may be tempted to define the form directly as an object inside a signal. While such an approach may seem more concise, typing into the individual fields does not dispatch reactivity updates, which is usually a deal breaker. Here’s an example StackBlitz with a component suffering from such an issue: Therefore, if you'd like to react to changes in the form fields, it's better to define each field as a separate signal. By defining each form field as a separate signal, you ensure that changes to individual fields trigger reactivity updates correctly. Example 2: A Complex Form with Signals You may see little benefit in using signals for simple forms like the login form above, but they truly shine when handling more complex forms. Let's explore a more intricate scenario - a user profile form that includes fields like firstName, lastName, email, phoneNumbers, and address. The phoneNumbers field is dynamic, allowing users to add or remove phone numbers as needed. Here's how this form might be defined using signals: ` > Notice that the phoneNumbers field is defined as a signal of an array of signals. This structure allows us to track changes to individual phone numbers and update the form state reactively. The addPhoneNumber and removePhoneNumber methods update the phoneNumbers signal array, triggering reactivity updates in the form. ` > In the template, we use the phoneNumbers signal array to dynamically render the phone number input fields. The addPhoneNumber and removePhoneNumber methods allow users to reactively add or remove phone numbers, updating the form state. Notice the usage of the track function, which is necessary to ensure that the ngFor directive tracks changes to the phoneNumbers array correctly. Here's a StackBlitz demo of the complex form example for you to play around with: Validating Forms with Signals Validation is critical to any form, ensuring that user input meets the required criteria before submission. With signals, validation can be handled in a reactive and declarative manner. In the complex form example above, we've implemented a computed signal called formValid, which checks whether all fields meet specific validation criteria. The validation logic can easily be customized to accommodate different rules, such as checking for valid email formats or ensuring that all required fields are filled out. Using signals for validation allows you to create more maintainable and testable code, as the validation rules are clearly defined and react automatically to changes in form fields. It can even be abstracted into a separate utility to make it reusable across different forms. In the complex form example, the formValid signal ensures that all required fields are filled and validates the email and phone numbers format. This approach to validation is a bit simple and needs to be better connected to the actual form fields. While it will work for many use cases, in some cases, you might want to wait until explicit "signal forms" support is added to Angular. Tim Deschryver started implementing some abstractions around signal forms, including validation and wrote an article about it. Let's see if something like this will be added to Angular in the future. Why Use Signals in Angular Forms? The adoption of signals in Angular provides a powerful new way to manage form state and reactivity. Signals offer a flexible, declarative approach that can simplify complex form handling by combining the strengths of template-driven forms and reactive forms. Here are some key benefits of using signals in Angular forms: 1. Declarative State Management: Signals allow you to define form fields and computed values declaratively, making your code more predictable and easier to understand. 2. Reactivity: Signals provide reactive updates to form fields, ensuring that changes to the form state trigger reactivity updates automatically. 3. Granular Control: Signals allow you to define form fields at a granular level, enabling fine-grained control over form state and validation. 4. Dynamic Forms: Signals can be used to create dynamic forms with fields that can be added or removed dynamically, providing a flexible way to handle complex form scenarios. 5. Simplicity: Signals can offer a simpler, more concise way to manage form states than traditional reactive forms, making building and maintaining complex forms easier. Conclusion In my previous articles, we explored the powerful features of Angular reactive forms, from dynamic form construction to custom form controls. With the introduction of signals, Angular developers have a new tool that merges the simplicity of template-driven forms with the reactivity of reactive forms. While many use cases warrant Reactive Forms, signals provide a fresh, powerful alternative for managing form state in Angular applications requiring a more straightforward, declarative approach. As Angular continues to evolve, experimenting with these new features will help you build more maintainable, performant applications. Happy coding!...

Oct 4, 2024

5 mins

AngularJavaScript

The HTML Dialog Element: Enhancing Accessibility and Ease of Use

The HTML Dialog Element: Enhancing Accessibility and Ease of Use Dialogs are a common component added to applications, whether on the web or in native applications. Traditionally there has not been a standard way of implementing these on the web, resulting in many ad-hoc implementations that don’t act consistently across different web applications. Often, commonly expected features are missing from dialogs due to the complexity of implementing them. However, web browsers now offer a standard dialog element. Why use the dialog element? The native dialog element streamlines the implementation of dialogs, modals, and other kinds of non-modal dialogs. It does this by implementing many of the features needed by dialogs for you that are already baked into the browser. This is helpful as it reduces the burden on the developer when making their applications accessible by ensuring that user expectations concerning interaction are met, and it can also potentially simplify the implementation of dialogs in general. Basic usage Adding a dialog using the new tag can be achieved with just a few lines of code. ` However, adding the dialog alone won’t do anything to the page. It will show up only once you call the .showModal() method against it. ` Then if you want to close it you can call the .close() method on the dialog, or press the escape key to close it, just like most other modals work. Also, note how a backdrop appears that darkens the rest of the page and prevents you from interacting with it. Neat! Accessibility and focus management Correctly handling focus is important when making your web applications accessible to all users. Typically you have to move the current focus to the active dialog when showing them, but with the dialog element that’s done for you. By default, the focus will be set on the first focusable element in the dialog. You can optionally change which element receives focus first by setting the autofocus attribute on the element you want the focus to start on, as seen in the previous example where that attribute was added to the close element. Using the .showModal() method to open the dialog also implicitly adds the dialog ARIA role to the dialog element. This helps screen readers understand that a modal has appeared and the screen so it can act accordingly. Adding forms to dialogs Forms can also be added to dialogs, and there’s even a special method value for them. If you add a element with the method set to dialog then the form will have some different behaviors that differ from the standard get and post form methods. First off, no external HTTP request will be made with this new method. What will happen instead is that when the form gets submitted, the returnValue property on the form element will be set to the value of the submit button in the form. So given this example form: ` The form element with the example-form id will have its returnValue set to Submit. In addition to that, the dialog will close immediately after the submit event is done being handled, though not before automatic form validation is done. If this fails then the invalid event will be emitted. You may have already noticed one caveat to all of this. You might not want the form to close automatically when the submit handler is done running. If you perform an asynchronous request with an API or server you may want to wait for a response and show any errors that occur before dismissing the dialog. In this case, you can call event.preventDefault() in the submit event listener like so: ` Once your desired response comes back from the server, you can close it manually by using the .close() method on the dialog. Enhancing the backdrop The backdrop behind the dialog is a mostly translucent gray background by default. However, that backdrop is fully customizable using the ::backdrop pseudo-element. With it, you can set a background-color to any value you want, including gradients, images, etc. You may also want to make clicking the backdrop dismiss the modal, as this is a commonly implemented feature of them. By default, the <dialog> element doesn’t do this for us. There are a couple of changes that we can make to the dialog to get this working. First, an event listener is needed so that we know when the user clicks away from the dialog. ` Alone this event listener looks strange. It appears to dismiss the dialog whenever the dialog is clicked, not the backdrop. That’s the opposite of what we want to do. Unfortunately, you cannot listen for a click event on the backdrop as it is considered to be part of the dialog itself. Adding this event listener by itself will effectively make clicking anywhere on the page dismiss the dialog. To correct for this we need to wrap the contents of the dialog content with another element that will effectively mask the dialog and receive the click instead. A simple element can do! ` Even this isn’t perfect though as the contents of the div may have elements with margins in them that will push the div down, resulting in clicks close to the edges of the dialog to dismiss it. This can be resolved by adding a couple of styles the the wrapping div that will make the margin stay contained within the wrapper element. The dialog element itself also has some default padding that will exacerbate this issue. ` The wrapping div can be made into an inline-block element to contain the margin, and by moving the padding from the parent dialog to the wrapper, clicks made in the padded portions of the dialog will now interact with the wrapper element instead ensuring it won’t be dismissed. Conclusion Using the dialog element offers significant advantages for creating dialogs and modals by simplifying implementation with reasonable default behavior, enhancing accessibility for users that need assistive technologies such as screen readers by using automatic ARIA role assignment, tailored support for form elements, and flexible styling options....

Oct 25, 2024

4 mins

HTMLJavaScript

Svelte 5 is Here!

Svelte 5 was finally released after a long time in development. Fortunately, we've been able to test it for some time, and now it has a stable release. Let's dig into its features and why this is such a significant change, even though Svelte 4 code is almost 100% compatible. Svelte syntax everywhere This is one of my favorite additions. Previously, Svelte syntax was limited to a component element. Refactoring code from a component and moving it to a JavaScript file worked differently. Now you can use the .svelte.js or .svelte.ts extension, which allows you to use the same syntax everywhere. It's important to note that it's a way to express that this is not just JS, and what you write may be compiled to something else, just like .svelte files are not just html even though they look very similar. Runes The introduction of runes is one of the most significant changes in Svelte. Many users felt attracted to variables being instantly reactive in previous versions. ` There was, however, a lot of magic underneath and a considerable amount of work from the compiler to make it behave reactively. $state In Svelte 5, a reactive variable has to be explicitly declared using the $state rune, which brings a clear distinction between what is reactive and what isn’t. ` In the previous code, $state is not an actual function being called; it's a hint for the compiler to do something special with this declaration. Rune names always start with a dollar sign ($) and do not need to be imported. However, there’s much more to the changes than just the way we declare reactive variables. Runes bring a lot of new features that make Svelte 5 a great improvement. In Svelte 5, objects or arrays use Proxies to allow for granular reactivity, meaning that individual properties in an object are reactive, even if they are nested objects or arrays. If you modify a property, it will only update that property and will not trigger an update on the whole object. It also supports triggering updates when methods like array.push are called. In previous versions, an assignment was required to trigger an update: ` To have a similar behavior of svelte 4 (no deep reactivity), use the $state.raw() rune. This syntax of .* is common for related features of a rune: $state.raw() will require an assignment to trigger reactivity. ` Because proxies are used, you may need to extract the underlying state instead of the proxy itself. In that case, $state.snapshot() should be used: ` $derived We will use $derived and $derived.by to declare a derived state. The two runes are essentially the same, except one allows us to use a function instead of an expression, allowing for more complex operations to calculate the derived values. ` $effect Effects are useful for running something triggered by a change in state. One of the things you'll note from the $effect rune is that dependencies don't need to be explicit. Those will be picked from reactive values read synchronously in the body of the effect function. ` Something to bear in mind is that these dependencies are picked each time the effect runs. The values read during the last run become the dependencies of the effect. ` Depending on the result of the random method, foo or bar will stop being a dependency of the effect. You should place them outside the condition so they can trigger reruns of the effect. *Variants* of the effect rune are $effect.pre, which runs before a DOM update, and $effect.tracking(), which checks for the context of the effect (true for an effect inside an effect or in the template). $props This rune replaces the export let keywords used in previous versions to define a component's props. To use the $props syntax, we can consider it to return an object with all the properties a component receives. We can use JavaScript syntax to destructure it or use the rest property if we want to retrieve every property not explicitly destructured.. ` $bindable If you want to mutate a prop so that the change flows back to the parent, you can use the $bindable prop to make it work in both directions. A parent component can pass a value to a child component, and the child component is able to modify it, returning the data back to the parent component. ` $inspect The $inspect rune only works in dev mode and will track dependencies deeply. By default, it will call console.log with the provided argument whenever it detects a change. To change the underlying function, use $inspect.with().with): ` $host The host rune gives access to the host element when compiling as a custom element: ` ` Other changes Another important change is that component events are just props in Svelte 5, so you can destructure them using the $props() rune: ` A special children property can be used to project content into a component instead of using slots. Inside the components, use the [@render[(https://svelte.dev/docs/svelte/@render) tag to place them. ` Optional chaining (?.) prevents from attempting to render it if no children are passed in. If you need to render different components in different places (named slots before Svelte 5, you can pass them as any other prop, and use @render with them. Snippets Snippets allow us to declare markup slices and render them conveniently using the render tag (@render). They can take any number of arguments. ` Snippets can also be passed as props to other components. ` ` Conclusion Some exciting changes to the Svelte syntax were introduced while, at the same time, maximum compatibility efforts were made. This was a massive rewrite with numerous improvements in terms of performance, bundle size, and DX. Besides that, a new CLI has been released, making the whole experience of starting a project or adding features delightful. If you haven't tried Svelte before, it's a great time to try it now....

Nov 27, 2024

4 mins

Svelte

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Making Seamless Page Transitions with the View Transitions API

Make Seamless Page Transitions using the View Transitions API

What is the View Transitions API?

Using the View Transitions API for SPAs

Using the View Transitions API for MPAs

Conclusion

Jamie Kuppens

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