General

Lit 2.0 Released: Building Fast and Lightweight Web Components

Published May 17, 2021

Updated Feb 14, 2023

4 min read

This article was written over 18 months ago and may contain information that is out of date. Some content may be relevant but please refer to the relevant official documentation or available resources for the latest information.

In the past months, I've been actively using Web Components to build single-page applications. It has been a great experience so far, not only because I learned a lot about the latest web standards, but also because the web applications ended up being quite fast.

The Web Component development story is not something new. In fact, it has been nearly three years since LitElement was introduced as a base class to build Web Components using JavaScript with the addition of great support from TypeScript. On the other hand, lit-html had been released almost four years ago as a way to create small and fast HTML templates in JavaScript.

As it was expected, these two worlds evolved favorably. Lit 2.0 was announced as a single library with a major update promising simple and fast Web Components.

What's New?

Lit 2.0 is coming out with a lot of great new features.

Smaller

The templating system of Lit 2.0 weights around 2.7 KB minified, and gzipped(compressed). Including the component base + reactive elements, it weights 5.8 KB.

The previous image shows the bundle size for lit@2.0.0-rc.1 from the BundlePhobia tool.

Better

This new release also includes several template improvements and a brand new class-based API for creating directives as the below example shows.

import {Directive, directive} from 'lit/directive.js';

class MyDirective extends Directive {
  render() {
    return `Hello world`;
  }
}

const hello = directive(MyDirective);
const template = html`<div>${hello()}</div>`;

Also, Lit 2.0 introduces the concept of Reactive Controllers which is a powerful primitive for code reuse and composition.

A Reactive Controller comes with the ability to "hook" into the component's lifecycle and it has its own creation API.

class MyElement extends LitElement {
  private clock = new MyReactiveController(this);
}

In the above code snippet, the component associated with the Reactive Controller instance is called the host component.

Faster

The Lit team has considered efficient rendering as one of the core values for the library since a good performance is always important when you're building for the web platform.

The library authors claim that Lit 2.0 is up to 20% faster on initial rendering and up to 15% faster on updates.

Also, it's good to know that Lit templates are efficient in keeping track of the UI, and only updates on re-rendering. These powerful features come along with interoperability in mind: they can work anywhere you use HTML with or without any framework.

Server-Side Rendering

Yes, Lit 2.0 comes with a server package for rendering Lit templates and components on the server, along with a flexible client-side "hydration".

The package name is below @lit-labs/ssr since it's a pre-release software at this time. However, it's expected to support a wide range of use cases:

App rendering frameworks built on top of web components.
Framework-specific plugins for rendering custom elements such as React or Angular.
Integration with static site generators.

You can be up-to-date about this server-side rendering support by following the news in this repository.

Connect with Lit

Lit 2.0 is not only about the cool features that are already described above, it comes along with a brand-new logo, a new website, and a welcoming community.

Why Lit?

The Web Components written with Lit are natively supported by browsers and they can be a perfect solution to share components across your application.

Also, Lit can be a useful solution to create your set of components through the Design System defined by your organization. This is even more helpful when your team uses multiple libraries and frameworks to build applications!

Community

You can be the first to know the good news about Lit and the upcoming releases. Share your ideas and projects with the community.

Join the conversations on Twitter: @buildWithLit
Send your issues or even better, help with Pull Requests on GitHub
Send your questions and help with technical issues on StackOverflow. Use lit, lit-html and lit-element as the related tags.
Finally, you can be part of lit-and-friends on Slack.

Just always remember to be nice to each other!

Playground

If you are a Developer who really enjoys and thinks through interactive examples, you cannot miss the Lit Playground website, which comes with the classic "Hello World" examples (using JavaScript and TypeScript), and others covering template concepts, directives, and more.

Conclusion

In case you were using both LitElement and lit-html (like me), it could be a great opportunity to upgrade your code to Lit 2.0. The general idea to do this involves updating the npm packages, importing paths, updating any custom directive, and using the class-based API or even adapt to minor breaking changes. Luckily, there is a guide available for upgrades.

If you're new in the world of Web Components, welcome! There is a step-by-step Lit tutorial available too.

Feel free to reach out on Twitter if you have any questions. Follow me on GitHub to see more about my work. Be ready for more articles about Lit on this blog.

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)

Luis Aviles
Luis is a Senior Software Engineer and Google Developer Expert in Web Technologies and Angular. He is an author of online courses, technical articles, and a public speaker. He has participated in different international technology conferences, giving technical talks, workshops, and training sessions. He’s passionate about the developer community and he loves to help junior developers and professionals to improve their skills. When he’s not coding, Luis is doing photography or Astrophotography.
@luixaviles @luixaviles

A Tale of Form Autofill, LitElement and the Shadow DOM

Many web applications utilize forms in places be it for logging in, making payments, or editing a user profile. As a user of web applications, you have probably noticed that the browser is able to autofill in certain fields when a form appears so that you don't have to do it yourself. If you've ever written an application in Lit though, you may have noticed that this doesn't always work as expected. The Problem I was working on a frontend project utilizing Lit and had to implement a login form. In essence these aren’t very complicated on the frontend side of life. You just need to define a form, put some input elements inside of it with the correct type attributes assigned to it, then you hook the form up to your backend, API, or whatever you need to call to authenticate by adding a submit handler. However, there was an issue. The autocomplete doesn’t appear to be working as expected. Only the username field was being filled, but not the password. When this happened, I made sure to check documentation sites such as MDN and looked at examples. But I couldn’t find any differences between theirs and mine. At some point, I prepared a minimal reproducible example without Lit, and I was able to get the form working fine, so it had to do something with my usage of Lit. After doing a little bit of research and some testing, I found out this happened because Lit relies very heavily on something known as the Shadow DOM. I don’t believe the Shadow DOM is necessarily supposed to break this functionality. But for most major browsers, it doesn’t play nice with autocomplete for the time being. I experienced slightly different behavior in all browsers, and the autocomplete even worked under Shadow DOM with Firefox in the Lit app I was working on. The solution I ended up settling on was ensuring the form was contained inside of the Light DOM instead of the Shadow DOM, whilst also allowing the Shadow DOM to continue to be used in places where autofillable forms are not present. In this article I will show you how to implement this solution, and how to deal with any problems that might arise from it. Shadow DOM vs. Light DOM The Shadow DOM is a feature that provides a way to encapsulate your components and prevent unrelated code and components from affecting them in undesired ways. Specifically, it allows for a way to prevent outside CSS from affecting your components and vice versa by scoping them to a specific shadow root. When it comes to the Light DOM, even if you’ve never heard of the term, you’ve probably used it. If you’ve ever worked on any website before, and interacted with the standard DOM tree, that is the Light DOM. The Light DOM, and any Shadow DOMs under it for that matter, can contain Shadow DOMs inside of them attached to elements. When you add a Lit component to a page, a shadow root will get attached to it that will contain its subelements, and prevent CSS from outside of that DOM from affecting it. Using Light DOM with Certain Web Components By default, Lit attaches a shadow root to all custom elements that extend from LitElement. However, web components don’t actually require a shadow root to function. We can do away with the shadow root by overriding the createRenderRoot method, and returning the web component itself: ` Although we can just put this method in any element we want exposed into the Light DOM. We can also make a new component called LightElement that overrides this method that we can extend from instead of LitElement on our own components. This will be useful later when we tackle another problem. Uh oh, where did my CSS styling and slots go? The issue with not using a shadow root is Lit has no way to encapsulate your component stylesheets anymore. As a result, your light components will now inherit styles from the root that they are contained in. For example, if your components are directly in the body of the page, then they will inherit all global styles on the page. Similarly when your light components are inside of a shadow root, they will inherit any styles attached to that shadow root. To resolve this issue, one could simply add style tags to the HTML template returned in the render() method, and accept that other stylesheets in the same root could affect your components. You can use naming conventions such as BEM for your CSS classes to mitigate this for the most part. Although this does work and is a very pragmatic solution, this solution does pollute the DOM with multiple duplicate stylesheets if more than one instance of your component is added to the DOM. Now, with the CSS problem solved, you can now have a functional Lit web component with form autofill for passwords and other autofillable data! You can view an example using this solution here. A Better Approach using Adopted Stylesheets For a login page where only one instance of the component is in the DOM tree at any given point, the aforementioned solution is not a problem at all. However, this can become a problem if whatever element you need to use the Light DOM with is used in lots of places or repeated many times on a page. An example of this would be a custom input element in a table that contains hundreds of rows. This can potentially cause performance issues, and also pollute the CSS inspector in your devtools resulting in a suboptimal experience both for users and yourself. The better, though still imperfect, way to work around this problem is to use the adopted stylesheets feature to attach stylesheets related to the web component to the root it is connected in, and reuse that same stylesheet across all instances of the node. Below is a function that tracks stylesheets using an id and injects them in the root node of the passed in element. Do note that, with this approach, it is still possible for your component’s styles to leak to other components within the same root. And like I advised earlier, you will need to take that into consideration when writing your styles. ` This solution works for most browsers, and a fallback is included for Safari as it doesn’t support adoptedStylesheets at the time of writing this article. For Safari we inject de-duplicated style elements at the root. This accomplishes the same result effectively. Let’s go over the evictDisconnectedRoots function that was called inside of the injection function. We need to ensure we clean up global state since the injection function relies on it to keep duplication to a minimum. Our global state holds references to document nodes and shadow roots that may no longer exist in the DOM. We want these to get cleaned up so as to not leak memory. Thankfully, this is easy to iterate through and check because of the isConnected property on nodes. ` Now we need to get our Lit component to use our new style injection function. This can be done by modifying our LightElement component, and having it iterate over its statically defined stylesheets and inject them. Since our injection function contains the de-duplication logic itself, we don’t need to concern ourselves with that here. ` With all that you should be able to get an autocompletable form just like the previous example. The full example using the adopted stylesheets approach can be found here. Conclusion I hope this article was helpful for helping you figure out how to implement autofillable forms in Lit. Both examples can be viewed in our blog demos repository. The example using basic style tags can be found here, and the one using adopted stylesheets can be found here....

Jun 7, 2023

6 mins

Lit

I Broke My Hand So You Don't Have To (First-Hand Accessibility Insights)

We take accessibility quite seriously here at This Dot because we know it's important. Still, throughout my career, I've seen many projects where accessibility was brushed aside for reasons like "our users don't really use keyboard shortcuts" or "we need to ship fast; we can add accessibility later." The truth is, that "later" often means "never." And it turns out, anyone could break their hand, like I did. I broke my dominant hand and spent four weeks in a cast, effectively rendering it useless and forcing me to work left-handed. I must thus apologize for the misleading title; this post should more accurately be dubbed "second-hand" accessibility insights. The Perspective of a Developer Firstly, it's not the end of the world. I adapted quickly to my temporary disability, which was, for the most part, a minor inconvenience. I had to type with one hand, obviously slower than my usual pace, but isn't a significant part of a software engineer's work focused on thinking? Here's what I did and learned: - I moved my mouse to the left and started using it with my left hand. I adapted quickly, but the experience wasn't as smooth as using my right hand. I could perform most tasks, but I needed to be more careful and precise. - Many actions require holding a key while pressing a mouse button (e.g., visiting links from the IDE), which is hard to do with one hand. - This led me to explore trackpad options. Apart from the Apple Magic Trackpad, choices were limited. As a Windows user (I know, sorry), that wasn't an option for me. I settled for a cheap trackpad from Amazon. A lot of tasks became easier; however, the trackpad eventually malfunctioned, sending me back to the mouse. - I don't know a lot of IDE shortcuts. I realized how much I've been relying on a mouse for my work, subconsciously refusing to learn new keyboard shortcuts (I'll be returning my senior engineer license shortly). So I learned a few new ones, which is good, I guess. - Some keyboard shortcuts are hard to press with one hand. If you find yourself in a similar situation, you may need to remap some of them. - Copilot became my best friend, saving me from a lot of slow typing, although I did have to correct and rewrite many of its suggestions. The Perspective of a User As a developer, I was able to get by and figure things out to be able to work effectively. As a user, however, I got to experience the other side of the coin and really feel the accessibility (or lack thereof) on the web. Here are a few insights I gained: - A lot of websites apparently _tried_ to implement keyboard navigation, but failed miserably. For example, a big e-commerce website I tried to use to shop for the aforementioned trackpad seemed to work fine with keyboard navigation at first, but once I focused on the search field, I found myself unable to tab out from it. When you make the effort to implement keyboard navigation, please make sure it works properly and it doesn't get broken with new changes. I wholeheartedly recommend having e2e tests (e.g. with Playwright) that verify the keyboard navigation works as expected. - A few websites and web apps I tried to use were completely unusable with the keyboard and were designed to be used with a mouse only. - Some sites had elaborate keyboard navigation, with custom keyboard shortcuts for different functionality. That took some time to figure out, and I reckon it's not as intuitive as the designers thought it would be. Once a user learns the shortcuts, however, it could make their life easier, I suppose. - A lot of interactive elements are much smaller than they should be, making it hard to accurately click on them with your weaker hand. Designers, I beg you, please make your buttons bigger. I once worked on an application that had a "gloves mode" for environments where the operators would be using gloves, and I feel like maybe the size we went with for the "gloves mode" should be the standard everywhere, especially as screens get bigger and bigger. - Misclicking is easy, especially using your weaker hand. Be it a mouse click or just hitting an Enter key on accident. Kudos to all the developers who thought about this and implemented a confirmation dialog or other safety measures to prevent users from accidentally deleting or posting something. I've however encountered a few apps that didn't have any of these, and those made me a bit anxious, to be honest. If this is something you haven't thought about when developing an app, please start doing so, you might save someone a lot of trouble. Some Second-Hand Insights I was only a little bit impaired by being temporarily one-handed and it was honestly a big pain. In this post, I've focused on my anecdotal experience as a developer and a user, covering mostly keyboard navigation and mouse usage. I can only imagine how frustrating it must be for visually impaired users, or users with other disabilities, to use the web. I must confess I haven't always been treating accessibility as a priority, but I've certainly learned my lesson. I will try to make sure all the apps I work on are accessible and inclusive, and I will try to test not only the keyboard navigation, ARIA attributes, and other accessibility features, but also the overall experience of using the app with a screen reader. I hope this post will at least plant a little seed in your head that makes you think about what it feels like to be disabled and what would the experience of a disabled person be like using the app you're working on. Conclusion: The Humbling Realities of Accessibility The past few weeks have been an eye-opening journey for me into the world of accessibility, exposing its importance not just in theory but in palpable, daily experiences. My short-term impairment allowed me to peek into a life where simple tasks aren't so simple, and convenient shortcuts are a maze of complications. It has been a humbling experience, but also an illuminating one. As developers and designers, we often get caught in the rush to innovate and to ship, leaving behind essential elements that make technology inclusive and humane. While my temporary disability was an inconvenience, it's permanent for many others. A broken hand made me realize how broken our approach towards accessibility often is. The key takeaway here isn't just a list of accessibility tips; it's an earnest appeal to empathize with your end-users. "Designing for all" is not a checkbox to tick off before a product launch; it's an ongoing commitment to the understanding that everyone interacts with technology differently. When being empathetic and sincerely thinking about accessibility, you never know whose life you could be making easier. After all, disability isn't a special condition; it's a part of the human condition. And if you still think "Our users don't really use keyboard shortcuts" or "We can add accessibility later," remember that you're not just failing a compliance checklist, you're failing real people....

Dec 6, 2023

5 mins

AccessibilityA11yWeb DevelopmentHTML

How to Update the Application Title based on Routing Changes in Angular

Have you tried to update the document's title of your application? Maybe you're thinking that applying interpolation should be enough: ` That solution is not going to work since the element is outside of the scope of the Angular application. In fact, the root component of your app is within tag, and the title is part of the element. Luckily, Angular provides the Title service with the methods to read the current title of the application, and a setTitle(title) to update that value. However, what happens if you need to update the title on routing changes? Also, you may consider updating it on certain components for Analytics purposes. In this blog post, I'll explain step-by-step how to create a custom Title service to have full control over the title of the current HTML document for your application. Project Setup Prerequisites You'll need to have installed the following tools in your local environment: - Node.js. Preferably the latest LTS version. - A package manager. You can use either NPM or Yarn. This tutorial will use NPM. Creating the Angular Project Let's assume we'll need to build an application with the following routes as requirements: ` Now, let's create the project from scratch using the Angular CLI tool. ` This command will initialize a base project using some configuration options: - --routing. It will create a routing module. - --prefix corp. It defines a prefix to be applied to the selectors for created components(corp in this case). The default value is app. - --style css. The file extension for the styling files. - --skip-tests. it avoids the generations of the .spec.ts files, which are used for testing Creating the Modules and Components Once we got the initial structure of the app, we'll continue running the following commands to create a separate module for /home and /products, which are the main paths of the project: ` * The --routing flag can be using also along with ng generate module to create a routing configuration file for that module. Creating the Title Service Similar to the previous section, we will create a shared module to hold the Title service. Both can be generated with the following commands: ` * The --module app flag is used to "link" the brand new module to the pre-existing app.module.ts file. The Routing Configuration Open the app-routing.module.ts file, and create the initial routes. ` * By default, the application will redirect to the home path. * When the router loads the home path, a HomeComponent will be rendered. * The products path will be loaded using the _lazy loading_ feature. Pay attention to the data provided to the home path. It contains the configured title through pageTitle string. Next, open the products-routing.module.ts file to enable an additional configuration to load the _Products_ and the _Product Detail_ page. ` * The router will render the ProductsComponent by default when the path matches to /products. This route also defines custom data to be rendered as titles later. * When the path also adds an Id on /products/:id, the router will render the ProductDetailComponent. The Title Service Implementation It's time to implement the custom Title Service for our application. ` The above service implementation could be understood in just a few steps. * First, we'll need to make sure to inject the Router, ActivatedRoute and Title services in the constructor. * The title$ attribute contains the initial value for the title("Corp"), which will be emitted through a _BehaviorSubject_. * The titleRoute$ is an Observable ready to emit any pageTitle value defined in the current route. It may use the parent's _pageTitle_ otherwise. * The titleState$ is an Observable ready to _listen_ to either title$ or titleRoute$ values. In case incoming value is defined, it will call the Angular Title service to perform the update. * The getPageTitle method will be in charge of obtaining the pageTitle of the current route if it is defined or the title of the parent otherwise. Injecting the Title Service One easy way to apply the custom Title Service in the whole application is by updating the app.module.ts file and injecting it into the constructor. ` In that way, once the default component gets rendered, the title will be displayed as Corp - Home. If you click on _Go to Products_ link, then a redirection will be performed and the Title service will be invoked again to display Corp - Products at this time. However, we may need to render a different title according to the product detail. In this case, we'll show Corp - Product Detail - :id where the Id matches with the current route parameter. ` Let's explain the implementation of this component: * The constructor injects the ActivatedRoute and the custom TitleService. * The productId$ is the _Observable_ which is going to emit the Id parameter every time it changes in the URL. * Once the component gets initialized, we'll need to _subscribe_ to the productId$ _Observable_ and then emit a new value for the title after creating a new string using the id. That's possible through the titleService.title$.next() method. * When the component gets _destroyed_, we'll need to _unsubscribe_ from the productIdSubscription. We're ready to go! Every time you select a product, the ProductDetail component will be rendered, and the title will be updated accordingly. Live Demo and Source Code Want to play around with the final application? Just open the following link in your browser: https://luixaviles.github.io/angular-update-title. Find the complete angular project in this GitHub repository: angular-update-title-service. Do not forget to give it a star ⭐️, and play around with the code. Feel free to reach out on Twitter if you have any questions. Follow me on GitHub to see more about my work....

Feb 16, 2022

5 mins

AngularTypeScriptWeb Development

AI Leadership: Data-Driven Decision Making & Avoiding "Analysis Paralysis" with Jerry Reghunadh

In this episode of Leadership Exchange, host Rob Ocel chats with Jerry Reghunadh, Senior Director of Enterprise Architecture at Data Nimbus, about leadership, AI adoption, and data-driven decision-making. Jerry shares his career journey, insights on leveraging tools like ChatGPT and Copilot, and strategies for building effective data pipelines. They explore how companies can avoid "analysis paralysis," adopt AI strategically, and evaluate new technologies to solve real-world problems. Tune in for practical advice on aligning innovation with business goals and staying competitive in a rapidly evolving tech landscape. Chapters 00:00 – Introduction 00:31 – Jerry’s Leadership Journey 02:01 – Discussing AI in Leadership 03:59 – Experimenting with AI Tools 06:24 – Overcoming Analysis Paralysis 09:18 – Importance of Early AI Adoption 13:12 – AI’s Impact on Efficiency 14:30 – Sponsor Message 16:26 – Setting Realistic Goals for AI 19:41 – Data Management and AI 23:09 – Is AI Just a Fad? 27:22 – Testing New Technologies 29:56 – Final Thoughts on AI 30:25 – Connect with Jerry 30:44 – Closing Remarks 31:20 – Outro Follow Jerry on Social Media Linkedin: https://www.linkedin.com/in/jerrymannel/ Sponsored by This Dot: thisdot.co...

Nov 18, 2024

1 min

AIEngineering Leadership

Let's innovate together!

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Whether it's modernization or custom software solutions, our team of experts can guide you through best practices and how to build scalable, performant software that lasts.

Lit 2.0 Released: Building Fast and Lightweight Web Components

What's New?

Smaller

Better

Faster

Server-Side Rendering

Connect with Lit

Why Lit?

Community

Playground

Conclusion

Luis Aviles

You might also like

A Tale of Form Autofill, LitElement and the Shadow DOM

I Broke My Hand So You Don't Have To (First-Hand Accessibility Insights)

How to Update the Application Title based on Routing Changes in Angular

AI Leadership: Data-Driven Decision Making & Avoiding "Analysis Paralysis" with Jerry Reghunadh

Let's innovate together!

You might also like

A Tale of Form Autofill, LitElement and the Shadow DOM

I Broke My Hand So You Don't Have To (First-Hand Accessibility Insights)

How to Update the Application Title based on Routing Changes in Angular

AI Leadership: Data-Driven Decision Making & Avoiding "Analysis Paralysis" with Jerry Reghunadh