Javascript

Learn the basics of CSS Filters

Published Oct 28, 2019

Updated Feb 14, 2023

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This article was written over 18 months ago and may contain information that is out of date.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

We never thought we could so easily kick up the visuals of our documents. Well now we can! CSS Filters are really cool visual effects, and the most fun part of CSS.

Now, without trying our hands at Photoshop or any other editing tool, we can give the same effects to our images using the CSS Filters.

The Blur Effect - The blur effect can be applied to an element using the blur() function. This function accepts CSS length value as a parameter which defines the blur radius. A larger value will create more blur. If no parameter is provided, then a value 0 is used.

.image-1 {
  -webkit-filter: blur(0|2px|5px); 
  filter: blur(0|2px|5px);
}

Image Brightness - The brightness() function can be used to set the brightness of an image. A value of 0% will create an image that is completely black. A value greater than 100% completely brightens the image while 100% or 1 leaves the image unchanged. Negative values are not allowed as a parameter to this function.

.image-1 {
  -webkit-filter: brightness(50%|100%|200%); 
  filter: brightness(50%|100%|200%);
}

Image Contrast - The contrast() function is used to adjust the contrast on an image. A value of 0% will create an image that is completely black. A value greater than 100% completely brightens the image while 100% or 1 leaves the image unchanged.

.image-1 {
  -webkit-filter: contrast(50%|100%|200%); 
  filter: contrast(50%|100%|200%);
}

Opacity - The opacity() function applies transparency to an image. Values between 0% and 100% are linear multipliers on the effect. The opacity filter effect is measured by the level of range from completely transparent to completely opaque.

.image-1 {
  -webkit-filter: opacity(10%|40%|80%); 
  filter: opacity(10%|40%|80%);
}

The Sepia Effect - The sepia filter effect is a brownish-grey to dark yellowish-brown tone imparted to an element and is expressed in percentages from 0% to 100%.

.image-1 {
  -webkit-filter: sepia(10%|40%|80%); 
  filter: sepia(10%|40%|80%);
}

Drop Shadow - This adds to a shadow to the image and is similar to what box-shadow does.

.image-1{
  drop-shadow(0);
}

.image-2 {
  -webkit-filter: drop-shadow(4px 4px 10px yellow);
  filter: drop-shadow(4px 4px 10px yellow);
}

.image-3 {
  -webkit-filter: drop-shadow(8px 8px 12px yellow);
  filter: drop-shadow(8px 8px 12px yellow);
}

Grayscale - The grayscale() CSS function converts the input image to grayscale. Values between 0% and 100% are linear multipliers on the effect.

.image-1 {
  -webkit-filter: grayscale(50%|100%|200%); 
  filter: grayscale(50%|100%|200%);
}

Hue Rotation - The CSS hue-rotate() function is used with the filter property to apply a hue rotation an image. A hue rotation is where you specify an angle around the color circle that the input samples will be adjusted by.

The CSS hue-rotate() function requires an argument to tell it how much to rotate the hue by.

.image-1 {
  -webkit-filter: hue-rotate(0|100deg|250deg); 
  filter: hue-rotate(0|100deg|250deg);
}

The Invert Effect - The invert() CSS function inverts the color samples in the input image. 0% (0) is the default and represents the original image. 100% will make the image completely inverted. Negative values are not allowed.

.image-1 {
  -webkit-filter: invert(0|40%|80%); 
  filter: invert(0|40%|80%);
}

Saturate - The saturate filter is used to vary the intensity of color in the element. A saturated element has overly bright colors; you can increase saturation on under-exposed images or vice versa. The amount of saturation can be expressed in percentages, where a value of 0% is completely un-saturated, and a value of 100% leaves the input unchanged.

.image-1 {
  -webkit-filter: saturate(10%|150%|350%); 
  filter: saturate(10%|150%|350%);
}

The CSS filters show the evolution of effects from SVG format and how effective they are. They make the images look more impactful with minimum efforts. Each filter has an essential purpose to apply the effect to a graphics element or container element

Current browser and user agent support can be found from the [@_"Can I use..." table for CSS3 Filter Effects] (https://caniuse.com/#search=css%20filter);

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.

:where functional pseudo-selectors :is valuable in CSS

If you’ve written CSS before, you’ve used pseudo selectors. Typically, we’d use them to style :hover events or select every :nth-of-type() In recent years CSS has become a lot more powerful, and with that, we now have many more pseudo-selectors available to use. Let’s explore some functional pseudo-selectors together and see how to use them to enhance our front-end code. Functional pseudo-classes While there are a wide range of pseudo-classes, I want to focus on the _functional_ ones today. :is :is works very similar to a regular CSS class list at first glance ` One of its main benefits is that you can group CSS classes to form more readable and maintainable conditions. ` For deep nesting, this can make your CSS significantly easier to understand, simplifying editing at a later date. ` You may be thinking that CSS has another solution that improves readability in a similar way: nesting. That’s true, and in this context, you can use them interchangeably, though the syntax is still shorter. ` However deeper nesting using nested CSS can become complex quickly. Sometimes it makes sense to use :is to help avoid this complexity. ` :is also provides a specificity modifier you don’t get with nested css. If you write: ` Every selector within the:is would be treated as if it had the same specificity value as the ID. With :is, the highest value applies to all other values within the :is. This does not apply to nested CSS. :not It does exactly what you think it does. The :not selector grabs everything _except_ the classes you define: ` Like the other pseudo-classes, you can negate multiple classes if you choose: ` This can be powerful when combined with other pseudo-selectors: ` :where Using the :where pseudo-class is great for creating low-specificity CSS. If you create a library or plugin that’s going to be used by other people and you want them to style it themselves, but don’t want it to appear ugly when they first set it up, :where is the way to do that. For example, let’s style all our links with an underline using :where ` With this approach, we can override our link’s default styles without having to create difficult to maintain CSS: ` If we didn't use :where above, import order would matter if we wanted to override this. But because we planned ahead, we can just use a standard a tag. Without using :where we’re stuck with options that are much harder to work with: ` :where also has the same benefits of class grouping that :is does but without the specificity, so you can do something like this and then override it easily later. ` :has One of the most powerful pseudo selectors is :has, which gives you the option to style a tag or class based on other classes or tags associated with it. ` An incredible benefit :has brings is the ability to create parent selector functionality. This gives you a wide variety of options to style the parent based on the state of the children. ` You can also combine this with the :not selector to select elements that don’t have specific children. ` Benefits of Pseudo-Classes Readability One of the benefits of all of these pseudo-selectors is that they can act similarly to nested CSS. It’s possible to use these to make your code more readable. ` Using :is this way is effectively the same as using nested CSS, but if you need lower specificity you could use :where, or :not if you want to exclude (instead of include) some classes. Functionality :not and :has provide new options which weren’t possible before, allowing you to style more dynamically and provide better experiences while simplifying your code. Before these options were available, the only solution was to style the code using JavaScript. While this technically allows you to achieve your styling goals, it’s not ideal. Mixing CSS operations into JS files makes it much harder to maintain long-term because it adds a layer of abstraction to your solution, while the built-in CSS option is much simpler. While :is and :where don’t provide as much new functionality, they still allow you to write more understandable CSS with less ambiguity or workarounds, making maintenance significantly easier. Summing up Modern CSS allows us to be much more flexible with our styles, all while writing less code. Simplifying CSS and removing the need to compensate, either by writing extra CSS or styling through JS, means our CSS files are more explicit and easier to maintain in the long term. They may not be needed often, but they’re an incredibly important part of your front-end toolbelt. Have you found any interesting ways to use functional pseudo-classes? Send us a post on X or message us on LinkedIn and show me what cool things you’ve made....

Aug 9, 2024

4 mins

CSS

The CSS / Utility hybrid approach with Tailwind v4

Just recently, the progress on the next major version of Tailwind CSS was open-sourced, along with a preview post. This is very exciting news to me, and I love the direction they’ve taken with this release. Tailwind can be a pretty polarizing topic among developers, but I believe that we can find some common ground and live in harmony. In this post, we’ll look at how the CSS + Tailwind hybrid approach is getting an upgrade in v4 and some of the patterns that we can take advantage of to provide a stellar styling experience on our websites. The hybrid approach It doesn’t matter what your personal take on Tailwind is, the fact is utility classes are an incredibly useful pattern for styling websites with CSS. I’m not sold on the hard-line, all-or-nothing approach that Tailwind has always recommended. Having a class string that extends way off the screen on an ultra-wide monitor is not pretty. Combining traditional CSS classes with utility classes helps cut down on the styling noise in your markup and provides some advantages when applied correctly. This post will cover some useful patterns and best practices for using CSS and Tailwind in harmony Tailwind going “CSS-native” In the v4 introduction post, they state A major goal of Tailwind CSS v4.0 is making the framework feel CSS-native, and less like a JavaScript library. I love that they are heading in this direction, and I’m imagining Tailwind as the toolkit for styling websites with CSS. It is going to replace the plethora of tools from the past and provide support for all the modern niceties like: * Importing CSS files with @import * Vendor prefixing _(no more autoprefixr)_ * Improved browser support for modern features like CSS nesting and media query ranges. This means less worry for us as developers. We can write our code and build our sites using the modern features that the platform provides without sweating all the other details and edge cases. The talented folks at Tailwind and the open-source community have our backs. Tailwind v4 CSS configuration The biggest step in the “CSS-native” direction and the feature that I’m most excited about is the CSS configuration. This is great for embracing CSS and Tailwind as one instead of two factions at battle. If you’ve been using Tailwind exclusively for a long time like I have, you might be out of touch with all the great features and tools that CSS provides out of the box now. This is a great opportunity to get back to learning and using the platform. In Tailwind v4 we do our configuration and theming with CSS variables. To get an idea of what this looks like check out the default theme on GitHub. In our configuration we can override any values from the default theme or extend it with new values. ` All the values from the theme are exposed as CSS variables. We can reference them in our CSS files or directly in our utility classes. ` ` Best practices for combining CSS with utility classes I can understand why Tailwind recommends using strictly utility classes. It’s easy to shoot yourself in the foot and run into the issues that utility classes set out to solve in the first place. I believe if you follow some general guidelines you can safely have the best of both worlds. Create focused/specialized classes CSS tends to get messy when we use classes that are overly specific with styles that apply to just one or a small number of use cases. Take a calendar where the days are custom checkboxes. You might have some pretty specialized styles for this bit of UI. ` Notice that we just add some specific styles that apply to this use case. This gives us the flexibility to keep composing our styles with utility classes. Some things are better left to utilities The best way to avoid wandering too far off the path of enlightenment is to stick with utility classes for certain (most?) things. Spacing and layouting are examples of things that are probably best left to utility classes. These typically vary all across a page, and encoding them in a class will make it a lot less flexible. A code smell to look out for: If you have abstracted something to a class and you end up overriding certain aspects of its styles in different places. Those styles should probably be utility classes. Classes as components Tailwind has always recommended using a component system for your UI components so that your utility classes are all defined in a single place. You don’t want to have to edit 50 different files to make a change to the style of your buttons across your website. I’ve found that defining things that might be simple “components” like buttons, badges, links, etc as classes works just as well in most cases. You can use Tailwind CSS with the @apply directive or traditional class definitions for this: ` You can even bring the BEM naming convention back to compose variants on top of base component styles. (or name them however you’d like!) ` Now we can easily define badges in our markup: ` Modern CSS and other interesting utility hybrid patterns I think a lot of us are realizing that modern CSS is pretty great. There are a ton of awesome new features gaining support across major browsers, like CSS nesting, container queries, and more! More and more people are also coming around to the utility of utility classes. If you want to dive deeper and see other interesting approaches and patterns when combining modern CSS with utility classes, check out the post: Modern CSS patterns in Campfire. Summary I’m looking forward to the Tailwind CSS configuration and other awesome updates coming in v4. Using Tailwind doesn’t have to be a one-size-fits-all approach. If you want to write some CSS, I say go for it! Hopefully, some of the points in this post will lead to success if you decide to do so....

May 10, 2024

4 mins

Tailwind CSSCSS

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

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

Let's innovate together!

We're ready to be your trusted technical partners in your digital innovation journey.

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.

Learn the basics of CSS Filters

You might also like

:where functional pseudo-selectors :is valuable in CSS

The CSS / Utility hybrid approach with Tailwind v4

Introduction to Zod for Data Validation

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

Let's innovate together!

You might also like

:where functional pseudo-selectors :is valuable in CSS

The CSS / Utility hybrid approach with Tailwind v4

Introduction to Zod for Data Validation

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