Twiv

Tailwind inline variants. A styling util (with type inference) that keeps your styles close to the markup. Like CVA without steriods.

// React example with as many concepts crammed in as possible
import { useTwiv } from "twiv";

interface PillProps {
  label: string;
  variant?: "success" | "failure";
  size: "small" | "large";
  className?: string;
}

function Pill({ label, variant, size = "small", className }: PillProps) {
  // useTwiw wraps and returns rawTwiv that checks the
  // state variables, reconciles any conflicts with twMerge
  // and returns the correct classes.
  const twiv = useTwiv([variant, size]);

  return (
    // twiv() is used in the className prop and will only allow
    // states that match the values from the passed variables
    <div
      className={twiv(
        {
          // Classes in BASE will always be applied...
          BASE: `
            text-white
            rounded
            border border-white
            bg-blue
          `,
          // ...unless overwritten in a state
          success: "bg-green",
          failure: "bg-red",
          banana: "bg-yellow", // This will throw a TS error since "banana" is not a defined state value
          small: "px-0.5 py-1",
          large: "px-1 py-2",
          // multiple states can be targeted with opcode strings (EXPERIMENTAL)
          ["ANY: success failure"]: "font-bold", // applies the classes if any state matches
          ["ALL: success large"]: "text-lg", // applies classes if all states match
          // (if two active states have conflicting classes, the class in the last state will be picked)
        },
        // twiv() also accepts an override as the second parameter
        className,
      )}
    >
      {label}
    </div>
  );
}

Installation

It's an NPM package. Any eqivalent of npm install twiv works.

What is Twiv?

Twiv is a small util function that makes it easier to manage Tailwind classes based on typed component props.

Why use Twiv?

TL;DR: Use this lib if you want some of the power of CVA, while still keeping styling simple and close to the markup.

Tailwind has many long-term benefits, but two of its nicest day-to-day features is the colocation of styles and markup, and that you don't need to name your elements. However, this simple model breaks as soon as we want to work with variants.

The most common ways to solve this is by using clsx, tailwind-merge or class-variance-authority. These come with their own set of drawbacks:

• class-variance-authority is a really powerful alternative, but its recommended usage forces you to define your styles outside of the markup, and come up with names for each element. Sometimes CVA's power can also lead us to add more complexity to a component than necessary. It's a great library for those really complex cases though.
• clsx and tailwind-merge can do inline variants really well, but checking against many state values can get messy, and sometimes we find ourselves writing more checks than class names. They're great libraries for the simpler cases though.

Twiv aims to be somewhere inbetween complex and simple, as that's where the complexity of most components should be.

Will Twiv work with my framework of choice?

Yes! Currently, there is a vanilla implementation and a React hook, but Twiv exposes a function called rawTwiv that can be used to write bindings for any other framework. Please submit a PR if you give it a go!

---

---

API

useTwiv(variantNames: [<string union type prop>])

or

vanillaTwiv(variantNames: [<string union type prop>])

returns:

twiv(
  variantStyleObject: {
    key: <variant state name or opcode string>,
    value: <Tailwind class string>
  },
  override: <Tailwind class string>)`

useTwiv and vanillaTwiv are interchangeable. useTwiv is just being memoized for better React performance.

---

variantNames

An array of props used to select the correct state styles. Each variant name needs to be a variable with a string union type.

---

variantStyleObject

An object with key-value pairs.

variantStyleObject key

Can be one of three values:

• BASE: This will always be applied regardless of state. Syntax is chosen to match Tailwinds DEFAULT config naming convention.

• variant state name: Will be constrained to the possible values of the variantNames props.

• Opcode string (experimental): A Twiv opcode followed by multiple state names, all separated by a space. Very limited type constraints here due to poor dynamic string typing in TS. Some constraints exist, but make sure to check your spelling. Two opcodes exist right now:

  • ALL: <list of variant state names>: Will be applied of all states match.
  • ANY: <list of variant state names>: Will be applies if at least one of the states match.

variantStyleObject value

A string of Tailwind class names.

If multiple states are true and they have clashing Tailwind class names, Twiv will select the the last occurrence of the class name.

---

override

A Tailwind class string that will override all other clashing Tailwind class names.

---

---

Roadmap

• Evaluate the experimental Opcodes feature (#2):
  • Try out performance.
  • Try out ergonomics.
  • Improve typings.
  • Could the same problem be solved in a better way?
• Add object notation (#1)?
• Add an Advanced examples section to the docs (#4).
• Add some actions to run tests, check coverage, do release branches and all that other cool stuff.