Javascript

Utilizing Cypress Testing in a Multi-App Monorepo

Published Jul 7, 2022

Updated Feb 13, 2023

6 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This article was written over 18 months ago and may contain information that is out of date.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.

For web developers, Cypress is a pretty well-understood testing library that everyone has at least come across or heard of. Getting it set up for an app is pretty straightforward, and you can be off and writing tests in a matter of minutes. But what if you have a monorepo with multiple apps? Do you set up a per-app test suite and manage multiple sets of code in multiple places? Or have you already set that up and noticed that there's a lot of redundancy with potentially shared code that you'd like to refactor into one place?

I was recently tasked with setting up such a Cypress testing structure in our Showcase section for our starter.dev project. The idea of the Showcases is that we utilized each of our framework packages to create a GitHub clone as an advanced example of an implementation of each. So they all have the same exact UI to the user, but underneath the hood, they all utilize different sets of technologies for the JavaScript framework, GraphQL/Rest, or CSS libraries.

I instantly figured that there had to be a way to write one set of tests that could be utilized against each app, and all I had to do was unify the data-testid attributes across all of the apps. But how do you set it up to automate the process, and against so many different apps? Would it even be possible to start, test, and stop each app through a script? Thankfully, the answer is yes -- and this blog will document and explain a structure that I used when solving that problem.

Prerequisites

If you've already been developing in a monorepo and have everything set up for that, you likely already have all requirements necessary to install Cypress. However, if you're not and you're setting everything up from scratch, the Cypress docs list a few system requirements:

macOS 10.9 and above (64-bit only)
Linux Ubuntu 12.04 and above, Fedora 21 and Debian 8 (64-bit only)
Windows 7 and above (64-bit only)

If you're on a Linux distrobution, pay special attention to the dependencies you'll be needing as well. If you're using npm, you'll need:

Node.js 12 or 14 and above

It's possible to download Cypress directly, but I don't recommend that approach for the purposes of this guide.

Project Structure

For this example, I will be showing the structure I used in the starter.dev GitHub Showcases repository. But hopefully it demonstrates that it's flexible enough to be used on any monorepo structure with any number of apps. The folder structure will look something like this when we're done (showing just two apps and the relevant folders/files for succinctness):

project/
├── app1/
│   ├── src/
│   └── package.json
├── app2/
│   ├── src/
│   └── package.json
└── tests-e2e/
    ├── package.json
    ├── yarn.lock
    └── cypress/
        ├── configs/
        ├── fixtures/
        ├── integration/
        ├── plugins/
        └── support/

Installation

In the root of your project, you'll want to make your directory where your Cypress tests will exist (replace tests-e2e with whatever you'd like your folder to be called):

mkdir tests-e2e
cd tests-e2e

Then, once inside this folder, install Cypress via npm:

npm install cypress --save-dev

Or via yarn:

yarn add cypress --dev

Next, we'll install start-server-and-test, which will be needed later on to automate starting our apps and running our test suite against them. Let's also install TypeScript:

npm install start-server-and-test --save-dev
npm install typescript

Or via yarn:

yarn add start-server-and-test --dev
yarn add typescript

In the newly created package.json in this folder, let's add a basic script to open Cypress:

{
  "scripts": {
    "cypress:open": "cypress open"
  },
  "dependencies": {
    "cypress": "^10.0.3",
    "typescript": "^4.7.3"
  },
  "devDependencies": {
    "start-server-and-test": "^1.14.0"
  }
}

Configuration

Now that we have everything installed, we can start configuring Cypress. Let's open Cypress via the newly created script in our last step, npm run cypress:open or yarn run cypress:open. Once Cypress opens, select the E2E Testing configuration and click continue at the bottom of the list to create all the default files (make sure to read what each one does if this is your first time using Cypress!).

You should see in your folder structure that Cypress created a number of files and folders automatically, but let's create a few additional folders:

mkdir cypress/configs
mkdir cypress/e2e       #mkdir cypress/integration if under Cypress 10
mkdir cypress/plugins

Inside cypress/configs let's create a file called app1.config.js, or app1.json if you're using a Cypress version older than 10 (replace app1 with the name of one of the apps you want to test against):

module.exports = defineConfig({
  startCommand: 'yarn dev',
  e2e: {
    setupNodeEvents(on, config) {},
    baseUrl: 'http://localhost:3000',
  },
})

Just regular JSON format for versions prior to Cypress 10:

{
  "baseUrl": "http://localhost:3000",
  "startCommand": "yarn dev",
  "integrationFolder": "cypress/integration"
}

A couple notes, baseUrl is the URL your app will deploy on when started up, startCommand is the commmand your app uses to start (for me, it was different for a few different apps, but if yours all use the same command you may not need this), and integrationFolder is where all the test .spec files will be. This can be customized if you've already decided that you'd like your tests to be written separately and/or only one of them will need unique tests, etc. But we can leave it alone for now.

Additionally, Cypress has quite a few configuration options. But, the one I'd like to point out specifically is the env option. Just like a .env file, you can utilize this to pass in specific parameters or options into your Cypress tests. Specifically, the different apps I was getting this test suite working against handled auth differently in a few cases, so I needed to visit a specific URL to fire off a redirect/auth chain to mock its state.

It looks like this (will be the same in any version of Cypress):

"env": {
    "authUrl": "/"
}

This may not be something you specifically need yourself, but you can pass in whatever you need for your specific apps, and it will only inject into the Cypress state for that app's Cypress config file. So, maybe you could use this to get the name of what app you're testing, etc.

Next, let's add a basic test file inside cypress/e2e or cypress/integration if under Cypress 10. Call it whatever you'd like, but I'll name it first-test.cy.ts (or first-test.spec.ts if you're using a Cypress version older than 10):

describe('My First Test', () => {
  it('Does not do much!', () => {
    expect(true).to.equal(true)
  })
})

Lastly, let's set up a few run scripts to automate running against all our apps. Update the scripts section of your package.json as such:

"scripts": {
    "cypress:open": "cypress open",
    "cypress:run": "cypress run --config-file $CYPRESS_CONFIG",
    "start": "START_COMMAND=`node -p \"require('$CYPRESS_CONFIG').startCommand\"` && cd ../$TARGET_APP && $START_COMMAND",
    "test": "CYPRESS_CONFIG=./cypress/configs/$TARGET_APP.config.ts BASE_URL=`node -p \"require('$CYPRESS_CONFIG').baseUrl\"` && CYPRESS_CONFIG=$CYPRESS_CONFIG start-server-and-test start $BASE_URL cypress:run",
    "test:watch": "yarn run cypress open --config-file cypress/configs/$TARGET_APP.config.ts"
}

For Cypress versions prior to 10:

"scripts": {
    "cypress:open": "cypress open",
    "cypress:run": "cypress run --config-file $CYPRESS_CONFIG",
    "start": "START_COMMAND=`node -p \"require('$CYPRESS_CONFIG').startCommand\"` && cd ../$TARGET_APP && $START_COMMAND",
    "test": "CYPRESS_CONFIG=./cypress/configs/$TARGET_APP.json BASE_URL=`node -p \"require('$CYPRESS_CONFIG').baseUrl\"` && CYPRESS_CONFIG=$CYPRESS_CONFIG start-server-and-test start $BASE_URL cypress:run",
    "test:watch": "yarn run cypress open --config-file cypress/configs/$TARGET_APP.json"
}

Tying it all together

If your entire project structure is set up properly and the file names and configurations all match names properly as described at the start of this blog, the scripts should work as is. The usage would looks like this:

TARGET_APP=app1 yarn run test

TARGET_APP=app1 yarn run test:watch

The first command, test, runs through all of the test specs that your config file you set up points to in the integrationFolder option in the command line. This option is good to quickly verify passing tests in the background and/or on your CI/CD pipeline. It first fetches the config file from cypress/config/, grabs the baseUrl from that config file, utilizes start-server-and-test to start your target app, and once it's running, it will run your test suite and tear everything down. This is a powerful and flexible option to then chain together running all your Cypress test suites for all your apps back to back from the same place.

The next option, test:watch is the option you'll want to use when developing tests. All it does is open Cypress against the target app's config file you've set up. Then in another process, you will still manually need to start your app locally. The benefit of this is once you change code in either the app or your Cypress test spec files, both will update automatically while everything is still open.

Conclusion

The solution laid out here isn't one for every single monorepo. However, I believe it can eliminate redundancy for certain types of monorepo structures where each app inside is similar enough, or even more rarely, each app is the same but the target deployments or underlying technology is different. Instead of a per-app Cypress installation and test suite in each app package, this may be exactly the solution to abstract or even refactor them to one single place. There's even flexibility built into this structure to allow a unique set of tests against only one or some of the apps you will need to have integration tests for.

Of course, this is only the first step. But hopefully it eliminates potentially the most problematic one. If you'd like to read further on writing Cypress tests themselves, we also have a great guide on writing tests themselves with Cypress that you can check out.

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About the author(s)

Brett Zeidler
Senior Software Engineer whose main experience was building and leading native mobile iOS applications, but is now looking to do the same in the web front-end world.
@https://github.com/brettzeidler

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

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

Getting Started with Angular: A Mobile Developer’s Approach

At many points in your career, you will find yourself picking up a new framework, platform, language, or (most likely) some combination of all three. In my case, I recently found myself looking for a change of pace, and ended up switching from working in native iOS as a Mobile Engineer to the world of JavaScript as a Front-End Engineer. Specifically, I started out with Angular. No matter how you slice it, learning something brand new can feel daunting — regardless of whether it is mid-career or otherwise. Luckily, Angular is extremely simple and quick to get set up . . . but getting an environment and project set up really is only a small part of the path to learning a platform, isn’t it? As I challenged myself to attempt to learn Angular as quickly as possible, I aimed to first break apart the approach by understanding: * What Angular is * What Angular's goal is * What the fundamental pieces of Angular are So, before we jump straight into some code, let's grasp these concepts first. What *is* Angular? First of all, Angular is not AngularJS. This was slightly confusing for me at first, and I made the mistake of mixing them up initially. Oops. At a macro level, Angular is a modern JavaScript framework that’s built on TypeScript, giving it access to static types, classes, and other elements provided by ES6. This allows code to organize and structure properly so it can be Object-Oriented, and allow for long-term maintenance at any scale, which will be important for the next fundamental concepts. What does Angular aim to achieve? Angular provides a platform to make single-page applications. I think it's important to point out the usage of the word platform, as Angular comes with quite a bit more to help us scale applications to any point we need. It ships with many integrated libraries (more on that in a bit), integration with numerous third-party libraries, and, maybe most importantly, the Angular CLI (command line interface), which gives us access to build, serve, test, and even ship our application. "Application" is also a very important distinction- that is, Angular (like many modern frameworks) aims to provide the tools to create responsive, smooth user experiences. What are the essential building blocks of Angular? To understand Angular, you have to understand what a Component is. But first, it may be easier to first visualize what makes an application: navbars, buttons, tables, table cells, and every other separately distinct building block you can visually see. In Angular, every single one of these is a Component, and everything else that exists is in service of these Components. For me, this is where it really started to click, since in iOS, the same fundamental principle exists: every single object on the screen *must* conform to UIView, including any View Controller. Angular, of course, is no different — the root view of the app itself is also a Component. Templates define the appearance of the Component via HTML. Angular extends the functionality of templates quite a bit through direct text interpolation, directives, and property/event binding. These, combined with CSS, can achieve essentially anything you need it to without having to entangle your Component's business logic with the presentation of said Component. The final core piece of the Angular paradigm is dependency injection. Essentially, dependency injection helps keep your Components extremely light, modular, and maintainable. So, say you have a table that needs data from a request sent to an API endpoint. You *could* just have the inner workings of a server fetch right there all in the component, but you likely have multiple places all over your application where you'll be making API requests, and have to duplicate that code. Instead, Angular lets you define a Service object that can handle that API request, and return the data directly to your component. You don't even need to instantiate the Service since Angular will just automatically do that for you once you inject the dependency to keep things even cleaner. Dependency injection, services, routing, etc. can feel daunting, but I think as long as you view everything else that isn't a Component solely existing to work *in favor* of Components, things become a lot clearer and you can start building apps the Angular way. Speaking of, let's do a bit of project setup, take a look at the structure, build it, and add a component. Prerequisties Now that we know what Angular is, we can finally start our first project. A couple things we will need first: * Visual Studio Code * NodeJS and NPM with at least a basic proficiency with a terminal * Some basic understanding of HTML and JavaScript/TypeScript Creating and running your first project With Node and NPM installed, we can install the Angular CLI with the following command: ` Then we create our first project with: ` Note: The above command will have a couple prompts for you. Answer yes to add Angular routing, and the style sheet format is up to you (I chose SCSS). You can just press enter on both prompts for the default setup as well. And finally, building and serving our new app locally: ` Open http://localhost:4200/ on your favorite browser to see what we just made. One note about ng serve is its ability to pick up code changes and update live — no waiting for build times just to see very small changes here. Nice. Project Structure Of course, it's helpful to know what the CLI just built out for us. Looking at our project structure in VS Code, we can see quite a bit of config files set up in the root directory. Of course, these are all important, but for now, let's focus on getting familiar with a few: * angular.json — This is the configuration file for CLI, so it knows how to build, serve, and test your app. Should be good to go right out of the box. * package.json — The file where the list of all your NPM dependencies live, the package-lock.json specifies the versions for these files (for my iOS friends, this is very similar to the podfile or build.gradle for my Android friends!). Whenever you install a Node package, the tool will automatically update these for you. * node_modules — With all the above dependencies installed, the .gitignore should be ignoring this directory by default, but it's good to know everything is there. Now that we're familiar with the housekeeping of the app, we can dig into the most important part: the code. In the src/app directory, we can see our first module, component, and the files that make it up. Let's ignore those files for now, and create our very first Component. Creating The First Component Within your terminal, we'll run the following command: ` With that, CLI should have made a directory in src/app/my-first-component and the following files: 1. my-first-component.component.ts — This is the file where the data and logic needed to update your Component's Template live. 2. my-first-component.component.html — The associated Template for the Component, where the HTML is defined to actually render our Component. 3. my-first-component.component.scss — The associated style sheet for the Template, where styles scoped only to this Component are defined. 4. my-first-component.component.spec.ts — The very first unit test for the Component, automatically generated by CLI. How nice! Within the component.ts file, let's take special note of the following: ` Here we can note the Template and style sheet URLs, but of particular note is the selector, in our case called app-my-first-component. This is the custom HTML tag we can now use anywhere our Component is imported in our project. The reason app is prepended to the front of the name is because we defined this Component within the app module, but you can absolutely change the name if you want. If we look back to the root app directory in src/app (taking special note of the exact same file structure we just created in my-first-component), let's open app.module.ts. The CLI has already created a declaration for our Component in the NgModule decorator, and imported MyFirstComponentComponent automatically for us. Let's actually get our newly created Component on the screen somewhere. Let's open app.component.html. There's quite a bit of HTML already in here, but we can leave it mostly alone for now. Really, we can throw our Component just about anywhere, but let's search for the following: ` And replace it with: ` Save your changes, and check your browser to see the following: Now that we've got it up on the screen, let's do some slight modification to get data from the logic to the Template. First, add the following inside the class definition of my-first-component.component.ts: ` Then, inside my-first-component.component.html, replace the Template definition with the following: ` The double bracket notation tells Angular to interpolate the value within, and dynamically pull the text defined in our class. Save both files, and you should see the following: Neat, right? Conclusion Whenever someone asks me how easy it is to get started doing native iOS app development, it's easy for me to boast that you can start a project, throw something in Interface Builder, and run it — all within a few minutes' time. Now, I (and hopefully you) can easily say the exact same about Angular. Of course, this is just a very small taste of what Angular has to offer, but hopefully instead of feeling initially lost in a sea of documentation, the relative simplicity of the platform will seem a lot more clear from the essence of what I described here from my journey of also having to learn Angular. From here, I think it's valuable to look through the incredible official Angular docs, and I'd recommend running through some of their tutorials as well....

Aug 26, 2021

8 mins

Mobile Web DevelopmentAngular

Understanding the Difference Between `:focus` and `:focus-visible` in CSS

Understanding the Difference Between :focus and :focus-visible in CSS I have learned my fair share about the importance of keyboard accessibility, so I know that visual indication of the focused element is very important. But the well-known :focus pseudo-class is not always the best fit for this job. That's where :focus-visible comes in. Let's look at the differences between these two pseudo-classes and explore the best practices for using them effectively. What is the :focus Pseudo-Class? The :focus pseudo-class is a CSS selector that applies styles to any element that receives focus, regardless of how that focus was triggered. This includes focus events from keyboard navigation, mouse clicks, and touch interactions. Example Usage of :focus ` In this example, the button will display a blue outline whenever it is focused, whether the user clicks on it with a mouse, taps it on a touchscreen, or navigates to it using the keyboard. What is the :focus-visible Pseudo-Class? The :focus-visible pseudo-class is more specialized. It only applies styles to an element when the browser determines that the focus should be visible. This typically occurs when the user navigates via the keyboard or assistive technologies rather than through mouse or touch input. Example Usage of :focus-visible ` Here, the button will only show a blue outline when focused through keyboard navigation or another input method that usually requires visible focus indicators. Key Differences Between :focus and :focus-visible :focus - Behavior: Applies to any element that receives focus, regardless of the input method. - Use Cases: Ensures that all interactions with the element are visually indicated, whether by mouse, keyboard, or touch. :focus-visible - Behavior: Applies styles only when the focus should be visible, such as using a keyboard or assistive technology. - Use Cases: Ideal for scenarios where you want to provide focus indicators only to keyboard and assistive technology users while avoiding unnecessary outlines for mouse and touch users, typically required by design. Accessibility Implications :focus - Pros: - Guarantees that all users can see when an element is focused, which is critical for accessibility. - Cons: - Can lead to a suboptimal experience for mouse users, as focus styles may appear unnecessarily during mouse interactions. :focus-visible - Pros: - Enhances user experience by showing focus indicators only when necessary, thus keeping the interface clean for mouse and touch users. - Tailors the experience for keyboard and assistive technology users, providing them with clear visual cues. - Cons: - Additional considerations may be required to ensure that focus indicators are not accidentally omitted, especially in older browsers that do not support :focus-visible. - There may be cases where you want to show focus indicators for all users, regardless of input method. Best Practices for Using :focus and :focus-visible To achieve the best accessibility and user experience, combining both :focus and :focus-visible in your CSS is often a good idea. Combining :focus and :focus-visible ` Here is a Stackblitz example of what such styling could look like for you to try out and play with. Additional Tips - Test with Keyboard and Assistive Technology: Ensure that your web application is navigable using a keyboard (Tab, Shift + Tab, etc.) and that focus indicators are visible for those who rely on them. It's never a bad idea to include accessibility testing in your e2e testing suite. - Provide Clear Focus Indicators: Make sure that focus indicators are prominent and easy to see. A subtle or hard-to-spot focus indicator can severely impact accessibility for users who rely on keyboard navigation. Conclusion The :focus-visible pseudo-class offers a more refined way to manage focus indicators, improving accessibility and user experience, particularly for keyboard and assistive technology users. By understanding the differences between :focus and :focus-visible, and applying best practices in your CSS, you can create more accessible and user-friendly web applications. Remember, accessibility should never be an afterthought. By thoughtfully applying focus styles, you ensure that all users, regardless of how they interact with your site, can easily navigate and interact....

Nov 8, 2024

3 mins

AccessibilityCSSPlaywright

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