Javascript

State of RxJS Wrap-up

Published May 22, 2023

Updated May 22, 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This article was written over 18 months ago and may contain information that is out of date.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 this State of RxJS event, our panelists discussed the current state of RxJS and the upcoming features and improvements of the highly anticipated RxJS 8 release.

In this wrap-up, we will talk about panel discussions with RxJS core team members, which is an in-depth exploration of the upcoming RxJS 8 release, highlighting its key features and performance enhancements. You can watch the full State of RxJS event on the This Dot Media YouTube Channel.

Here is a complete list of the host and panelists that participated in this online event.

Hosts:

Tracy Lee, CEO, This Dot Labs, @ladyleet
Ben Lesh, RxJs Core Team Lead, @BenLesh

Panelists:

Mladen Jakovljević, Frontend Web Developer, RxJS Core Team member, @jakovljeviMla
Moshe Kolodny, Senior Full Stack Engineer at Netflix, Previous RxJS Lead at Google, @mkldny
Marko Stanimirović, NgRx Core Team Member | GDE in Angular, @MarkoStDev

State of RxJS

Ben kicks off the discussion by updating everyone on the current state of RxJS. He starts off by recommending those using RxJS v6 to update to the current version 7.4 because it is about half the size of v6, and he says that v8 will reduce the size even further. There are also performance updates with 7.4 where the speeds improved 30 fold.

RxJS version 8 is currently in alpha! There are not as many breaking changes with this version. The major breaking change in this version is that they are removing the long deprecated APIs.

They are really wanting people to try things in the alpha version, especially the 408 loops to subscribe to observables. It is an interesting way to consume observables that use the platform, and may work really well with other people’s async await usage.

Operators

The team is currently trying to figure out a way to show people how they develop operators by giving them the means of developing operators. They currently have a problem where they externally tell people to develop an operator with this, you subscribe, and then you give this kind of hand rolled Observer there. Internally, they have a createOperatorSubscriber which replaces the operate function. They want a reference where you can see how to develop an operator using the ones already there to build your own.

There is also a plan to make sure that the RxJS library works as a utility library to work with any Observable that matches the contract.

Docs

Mladen gives an update of the docs for RxJS. He explains that there aren’t a lot of updates currently with the docs. He explains that there were some issues in the past with exporting operators from two places. There was also an issue with the Docs app build running in the pipeline. He explains that these issues should now be resolved, and that there hopefully won’t be any more issues there.

Pull requests are always welcome when working with RxJS docs. They try to stay on top of merge requests as well.

NgRx

Marko talks about NgRx and RxJS. He explains that RxJS is the main engine of NgRx for almost all of the libraries, especially State Management. A few packages, like direct store, implements a Redux pattern, but uses RxJS under the hood.

Pipe

Moshe brings up the typings for pipe. All of RxJS’s pipe methods and functions, including the new RxJS function, will work with any unary function.

General Questions

One of the first questions brought up was if RxJS should not be associated with Angular anymore. Ben brings up the fact that recently, there have been a lot of React people downloading RxJS.

Another question was why NgRx is switching to Signals. Marco talks about how NgRx is a group of libraries that is used in Angular. NgRx needs to be in accordance with Angular. One main reason is because of the performance improvements with the change detection strategy.

There were also other questions about contributing to RxJS and coming up with a way to utilize the docs for that. There are also questions about the RxJS community, and that there currently isn’t a discord or anything like that for it right now.

Conclusion

The panelists were very engaged, and there was a lot of dialogue about RxJS and the future that is to come with it. The question and answer portion at the end covered some great material that all the panelists took part in answering. You can watch the full State of RxJS event on the This Dot Media Youtube Channel.

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.

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About the author(s)

Bruce Wiggleston
@brucerw3 @BruceRW3

Using Custom Async Validators in Angular Reactive Forms

What is a validator in Angular? First, let's talk about Validators. What is a validator, and how we can use them to improve our forms. Ocasionally, we want to validate some input in our fields before submission, which will be validated against an asynchronous source. For instance, you may want to check if a label or some data exists before submission. In Angular, you can do this using Async Validators. Create a basic application We are going to create a very minimalist form that does one thing: check if the username already exists. In this case, we are going to use a mix of async and sync validators to accomplish our task. It's very common, in most registration forms, to require an unique username. Using an API call, we to capture if that username is already in use according to the database. ` Created a basic form that has a FormGroup called registrationForm, with 2 FormControl. Also, I added 2 sync validators for make the input required and also to check if the input has a minimum length, using Validators.required and Validators.minLength in each case. ` I'm using @angular/material just to simplify our styles, and because it provides a clean way to display errors using the mat-error component. This component will be shown to the user if the required error is present. The button also checks if the FormGroup is valid, otherwise it will be disabled. Async validators Our current app works pretty well, and in most cases, will meet all of the requirements. But what if we want to make sure that the username is unique before allowing the user to submit their information?. Creating an Async Validator could be simple. Let's find how to create it, and add it to our current form. ` Our method to check if the username already exists is called checkIfUsernameExists. It returns an observable with a 5 seconds delay to simulate a very slow API call. Now, we can create our Async Validator to check if the username exists against that method. ` Our UsernameValidator class takes our UserService as an argument. This method returns a AsyncValidatorFn which receives the FormControl that is placed on, providing us access to the current value. An AsyncValidatorFn must return either a promise or an Observable of type ValidationErrors. We use the RxJS map operator to check the value emitted, and either return null if the user doesn't exist, or return a ValidationError with an error type of usernameAlreadyExists. ` We import our UsernameValidator and UserService into our component, and declare in the constructor component. The UsernameValidator is added to our FormControl as the third parameter, calling the createValidator method, and passing a reference to the UserService. ` We update our template to check for an additional error called usernameAlreadyExists, so if our UserService finds that the username already exists, it will provide a to the user based on her status. > The validation status of the control. There are four possible validation status values: > > VALID: This control has passed all validation checks. > > INVALID: This control has failed at least one validation check. > > PENDING: This control is in the midst of conducting a validation check. > > DISABLED: This control is exempt from validation checks Let's see StackBlitz in action. Conclusion Creating beautiful forms for our web app might seem simple, but it's typically more complicated than one would expect. Sometimes, we also need to verify the information, because we don't want to blindly send data to the backend, and then reject it. This can lead to a poor experience for users and result in low adoption rates. Creating an AsyncValidator can help us improve the user-experience, and also avoid sending data to the backend, resulting in a rejection....

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State of Angular Ecosystem | December 2021

This is a recap from the event State of Angular Ecosystem, you can see the full watch on State of Angular Ecosystem | Dic 2021. This event was hosted by Rob Ocel, Software Architect and Engineering Lead at This Dot. What's is new on the Angular Ecosystem? What should be expect on the upcoming releases? How Angular ecosystem looks like in the future? Also, we had this amazing panel: - Minko Gechev, Software engineer at Google, Angular Core team. - Ben Lesh, RxJS core team lead. - Mark Whitfeld, Software engineer at Stackblitz, NGXS corea team lead. - Brandon Roberts, Senior Angular Engineer, Nrwl & NgRx maintainer. - James Daniels, Developer Relations, Firebase. - Jessica Janiuk, Senior Software Engineer, Google. RxJS updates (Ben Lesh) Weeks ago was introduced RxJS 7.4, the latest version from the RxJS team, which has many features, but first of all, the bundle size compared between RxJS 6 vs RxJS 7 (if you include everything RxJS exports, included new features!) was cut by almost the half, so if you are thinking to switch between those versions, you should go ahead. Now, v7 has tons of typings fixes/updates, but now requires TypeScript 4.2+. Most of the new features included in the new version are: - Top-level exports - Multi-cast simplified - Improved retry ergonomics - Animation Frames - New tap features - AsyncIterable support That's was most of the most importants features delivered on RxJS 7.4, but there is more such as: - Ajax/fetch improvements - Supporting for aborting promises & more... Regarding in how many downloads has RxJS, the downloads has increased consideraly since RxJS 6 in 2018. Now we can 30M downloads a week, back then in 2018 they have only 10M per week. Stackblitz (Mark Whitfeld) Now Stackbliz has support for Angular v13, this was thanks to the upgrade of Stackblitz v2, which runs over web-containers. This new upgrade to Stackblitz v2, avoid to have custom-code depending on which framework you are running, making Stackblitz more agnostic from the framework (Angular, React, Vue) you are using. In fact, there is no custom-code to support any of the most used frameworks. NGXS (Mark Whitfeld) Now NGXS has support for Angular v13, with this mayor release there are up-to-date with the latest version of Angular. They are working on deliver another big features too. Angular Core (Minko Gechev, Jessica Janiuk) Ivy Ivy now its the default engine to run compilation in Angular, which lead us a huge increase of performance vs versions who runs other engines to compile Angular. With the implementation of Ivy as default, we can see a: - 90% reduction of computational resources. - -50 mins faster build for the biggest app in Google. - Improved debuggability and profiling. - More effective relation between Github issues vs Fixes, thanks to a huge effort from the Team. - New system for RFC process. What's new in Angular v13? With the recent release of Angular v13 some new features are delivered, which include: - Removal of IE11 support (no more polyfills file, yaaaay) - Modern angular package format. - Partially compiled Angular - Removed UMD bundles - ES2020 output - Adobe font inlining - Webpack 5 cache - Dinamic validator control - Better a11y What are we building next? Some of the upcoming improvements are: - Extended analysis - Simplified factory API - Advanced guides - MDC Web Standalone components Maybe some of the biggest updates which are upcoming on the next versions of Angular are Standalone components, who will run without adding to any module. This Standalone component will be bootstrapped directly into the Angular module, and the bundle will be reduced significantly. NgRx (Brandon Roberts) The most recent version of NgRx added some new features as: - Angular v13 support - RxJS 7 support - Ivy compiled libraries support - Feature creators - Improved selectors - Contributors page Nx (Brandon Roberts) The recent release of Nx, which is v13.2, also now include Angular v13 support. Also NgRx v13, and NestJS 8 support was included in the most recen version. Now, there is a RxJS 7 upgrade option for Nx. AngularFire (James Daniels) The official library from Firebase to Angular also release some of the next features: - Firebase v9 support, entirely tree-shakable support, RxJS 7 & Angular v13 support. - Firebase v8 compatibility. - Internally uses AngularFire, increased agility and less duplication. - Partial compilation, Ivy support. - Powerful new schematics In the upcoming releases for AngularFire, the team is working to improve the next items: - Documentation drive - ng deploy capabilities - More schematics on the way... - Better bundling/rehydration - Prebuilt UI components Conclusion Angular v13 bring to us so many new features, therefore the Ecosystem of Angular is updating to support this new release. Some of the most libraries used with Angular are pushing forward and taking the framework from Google to the next level. Also the Angular team, is listening to the community and making the upcoming releases more beginner-friendly such as `Standalone components. As Angular dev, we celebrate the removal of IE11 support without that, we can take advantages of most CSS features who are not supported in that browser....

Dec 14, 2021

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State of Svelte Wrap-up

In this State of Svelte event, our panelists discussed updates, LTS releases, and APIs, with Node.js maintainers, technical steering committee members, and collaborators. In this wrap-up, we will take a deeper look into these latest developments, and explore what is on the horizon for Svelte. You can watch the full State of Svelte event on the This Dot Media YouTube Channel. Here is a complete list of the host and panelists that participated in this online event. Hosts: - Tracy Lee, CEO, This Dot Labs, @ladyleet - Rob Ocel, Team Lead & Software Architect, @robocell Panelists: - Scott Spence, Svelte Society, Developer Relations Engineer at Storyblok, @spences10 - Brittney Postma, Founder Svelte Sirens & Software Engineer Design Systems at Provi, @BrittneyPostma - Geoff Rich, Senior Software Engineer, Ordergroove | Svelte Core Team, @geoffrich_ - Simon Holthausen, Software Engineer at Vercel | Full-time Svelte maintainer, @dummdidumm_ - Kevin Åberg Kultalahti, Co-founder & Technical Community Builder at Svelte Society, Main Organizer at Svelte Summit, @kevmodrome Svelte 4 The chat got off to a great start with a discussion about Svelte 4, and what we can expect with that release. Simon spoke about how it will be more of a maintenance update than anything else. This version of Svelte will raise the minimum required Node version and use newer versions of Typescript as well. There will also be other minor breaking changes, but the release will mainly be focused on internally updating the repository by converting it to a mono-repo. As soon as these updates are done, Simon said they will immediately begin work on Svelte 5. Typescript and Svelte Scott brings up the reasons for not using Typescript in Svelte. Simon said a decision was made to transition the Svelte repository from using Typescript to using Javascript. There were questions about why types and type safety were being taken away from the repository. Simon clarified that the repository will be getting rid of .TS files, but they are not getting rid of type checking with Typescript, and the code will still be fully typed checked at the same level as before. The plan is to do it through JS Docs. JS Docs provides the same level of type safety you get through Typescript, but there is no longer a need for a compile step when using JS Docs. There is also no need to ship any Source Maps, and it should be easier to debug. Kevin also wanted to be clear that Typescript can still be used when building a Svelte app. Why Svelte? Rob notes that the official release of Svelte happened about 4 months ago, and asks the panelists how the launch has been going so far. Kevin goes first, talking about how everyone with whom he has talked about it has been very excited about it. He talks about how the form actions and data loading are very popular. In other frameworks, you have to attach event listeners, and then do the fetching on clients. Svelte simplifies all of that, and allows you to get rid of a lot of code by using the features in Svelte. Svelte REPL Kevin talks about the Svelte REPL, and how it plays into why Svelte is getting so big. Svelte isn’t just easy, it’s the fact that it is social in the fact that you can share a REPL and show someone how to do something with Svelte. If you have an issue, you can usually find a solution in the Svelte REPL. Server and Client Geoff talks about this aspect of Svelte. He says that they were treated as two separate entities, and there was talk about how to make them more interconnected so that it’s easier to use the server data, and get it into components. In SvelteKit, you have a load function in a separate file that defines how that data is loaded. Svelte also calls a JSON endpoint and then that component in the JSON data. State Management Geoff brings up the simple state management model that Svelte has, and they really don’t want to give that up by implementing too many things like short syntax. Simon adds that there is no real reason to bloat the syntax in the Svelte files. He doesn’t want the interoperability that Svelte currently offers. Signals vs Store A question is brought up about Signals vs Store, and if they are the same. Simon talks more about how they are related, but they are not necessarily the same. He explains that the API for Store is a little more settled right now where the API for Signals is a little more in exploration. Usability is also different because Signals is more primitive, and everything is composed of functions which you call in a certain way. With Stores, you wrap a store and map the values that are pushed into something different. How the panelists found out about Svelte The latter part of this event focused on how each panelist found Svelte and got involved with it. It was a very interesting part of the conversation to hear the backgrounds of each panelist, and why they got more and more involved with Svelte and everything that was going with it. It went very in depth, and would be worth exploring more by watching the conversation unfold on the event video. Conclusion The panelists were very engaged, and there was a lot of dialogue about Svelte and the exciting things being done. The panelists also finished by bringing up ways to get involved with the Svelte community. You can watch the full State of Svelte event on the This Dot Media Youtube Channel....

Apr 28, 2023

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Introduction to Zod for Data Validation

As web developers, we're often working with data from external sources like APIs we don't control or user inputs submitted to our backends. We can't always rely on this data to take the form we expect, and we can encounter unexpected errors when it deviates from expectations. But with the Zod library, we can define what our data ought to look like and parse the incoming data against those defined schemas. This lets us work with that data confidently, or to quickly throw an error when it isn't correct. Why use Zod? TypeScript is great for letting us define the shape of our data in our code. It helps us write more correct code the first time around by warning us if we are doing something we shouldn't. But TypeScript can't do everything for us. For example, we can define a variable as a string or a number, but we can't say "a string that starts with user_id_ and is 20 characters long" or "an integer between 1 and 5". There are limits to how much TypeScript can narrow down our data for us. Also, TypeScript is a tool for us developers. When we compile our code, our types are not available to the vanilla JavaScript. JavaScript can't validate that the data we actually use in our code matches what we thought we'd get when we wrote our TypeScript types unless you're willing to manually write code to perform those checks. This is where we can reach for a tool like Zod. With Zod, we can write data schemas. These schemas, in the simplest scenarios, look very much like TypeScript types. But we can do more with Zod than we can with TypeScript alone. Zod schemas let us create additional rules for data parsing and validation. A 20-character string that starts with user_id_? It's z.string().startsWith('user_id_').length(20). An integer between 1 and 5 inclusive? It's z.number().int().gte(1).lte(5). Zod's primitives give us many extra functions to be more specific about *exactly* what data we expect. Unlike TypeScript, Zod schemas aren't removed on compilation to JavaScript—we still have access to them! If our app receives some data, we can verify that it matches the expected shape by passing it to your Zod schema's parse function. You'll either get back your data in exactly the shape you defined in your schema, or Zod will give you an error to tell you what was wrong. Zod schemas aren't a replacement for TypeScript; rather, they are an excellent complement. Once we've defined our Zod schema, it's simple to derive a TypeScript type from it and to use that type as we normally would. But when we really need to be sure our data conforms to the schema, we can always parse the data with our schema for that extra confidence. Defining Data Schemas Zod schemas are the variables that define our expectations for the shape of our data, validate those expectations, and transform the data if necessary to match our desired shape. It's easy to start with simple schemas, and to add complexity as required. Zod provides different functions that represent data structures and related validation options, which can be combined to create larger schemas. In many cases, you'll probably be building a schema for a data object with properties of some primitive type. For example, here's a schema that would validate a JavaScript object representing an order for a pizza: ` Zod provides a number of primitives for defining schemas that line up with JavaScript primitives: string, number, bigint, boolean, date, symbol, undefined, and null. It also includes primitives void, any, unknown, and never for additional typing information. In addition to basic primitives, Zod can define object, array, and other native data structure schemas, as well as schemas for data structures not natively part of JavaScript like tuple and enum. The documentation contains considerable detail on the available data structures and how to use them. Parsing and Validating Data with Schemas With Zod schemas, you're not only telling your program what data should look like; you're also creating the tools to easily verify that the incoming data matches the schema definitions. This is where Zod really shines, as it greatly simplifies the process of validating data like user inputs or third party API responses. Let's say you're writing a website form to register new users. At a minimum, you'll need to make sure the new user's email address is a valid email address. For a password, we'll ask for something at least 8 characters long and including one letter, one number, and one special character. (Yes, this is not really the best way to write strong passwords; but for the sake of showing off how Zod works, we're going with it.) We'll also ask the user to confirm their password by typing it twice. First, let's create a Zod schema to model these inputs: ` So far, this schema is pretty basic. It's only making sure that whatever the user types as an email is an email, and it's checking that the password is at least 8 characters long. But it is *not* checking if password and confirmPassword match, nor checking for the complexity requirements. Let's enhance our schema to fix that! ` By adding refine with a custom validation function, we have been able to verify that the passwords match. If they don't, parsing will give us an error to let us know that the data was invalid. We can also chain refine functions to add checks for our password complexity rules: ` Here we've chained multiple refine functions. You could alternatively use superRefine, which gives you even more fine grained control. Now that we've built out our schema and added refinements for extra validation, we can parse some user inputs. Let's see two test cases: one that's bound to fail, and one that will succeed. ` There are two main ways we can use our schema to validate our data: parse and safeParse. The main difference is that parse will throw an error if validation fails, while safeParse will return an object with a success property of either true or false, and either a data property with your parsed data or an error property with the details of a ZodError explaining why the parsing failed. In the case of our example data, userInput2 will parse just fine and return the data for you to use. But userInput1 will create a ZodError listing all of the ways it has failed validation. ` ` We can use these error messages to communicate to the user how they need to fix their form inputs if validation fails. Each error in the list describes the validation failure and gives us a human readable message to go with it. You'll notice that the validation errors for checking for a valid email and for checking password length have a lot of details, but we've got three items at the end of the error list that don't really tell us anything useful: just a custom error of Invalid input. The first is from our refine checking if the passwords match, and the second two are from our refine functions checking for password complexity (numbers and special characters). Let's modify our refine functions so that these errors are useful! We'll add our own error parameters to customize the message we get back and the path to the data that failed validation. ` Now, our error messages from failures in refine are informative! You can figure out which form fields aren't validating from the path, and then display the messages next to form fields to let the user know how to remedy the error. ` By giving our refine checks a custom path and message, we can make better use of the returned errors. In this case, we can highlight specific problem form fields for the user and give them the message about what is wrong. Integrating with TypeScript Integrating Zod with TypeScript is very easy. Using z.infer<typeof YourSchema> will allow you to avoid writing extra TypeScript types that merely reflect the intent of your Zod schemas. You can create a type from any Zod schema like so: ` Using a TypeScript type derived from a Zod schema does *not* give you any extra level of data validation at the type level beyond what TypeScript is capable of. If you create a type from z.string.min(3).max(20), the TypeScript type will still just be string. And when compiled to JavaScript, even that will be gone! That's why you still need to use parse/safeParse on incoming data to validate it before proceeding as if it really does match your requirements. A common pattern with inferring types from Zod schemas is to use the same name for both. Because the schema is a variable, there's no name conflict if the type uses the same name. However, I find that this can lead to confusing situations when trying to import one or the other—my personal preference is to name the Zod schema with Schema at the end to make it clear which is which. Conclusion Zod is an excellent tool for easily and confidently asserting that the data you're working with is exactly the sort of data you were expecting. It gives us the ability to assert at runtime that we've got what we wanted, and allows us to then craft strategies to handle what happens if that data is wrong. Combined with the ability to infer TypeScript types from Zod schemas, it lets us write and run more reliable code with greater confidence....

Nov 15, 2024

7 mins

JavaScriptZod

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State of RxJS Wrap-up

Bruce Wiggleston

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