A tool for managing React component class names, variants and styles.
const SomeButton = ({ isLoading, ...props }) => {
const activeClass = isLoading
? "bg-blue-400 text-white"
: "bg-blue-800 text-blue-200";
return (
<button
{...props}
className={`transition-all mt-5 border-1 md:text-lg text-normal ${someConfig.transitionDurationEaseClass} ${activeClass} ${
props.className || ""
}`}
>
{props.children}
</button>
);
};const SomeButton = rc.button`
text-normal
md:text-lg
mt-5
border-1
transition-all
${someConfig.transitionDurationEaseClass}
${({ $isLoading }) => ($isLoading ? "opacity-90 pointer-events-none" : "")}
`;- Class name-focused components
- Variants
- Extend components
- Dynamic styles
- TypeScript support
- Tested with SSR Frameworks
- Classname merging
- Features
- Getting started
- Basic usage
- Usage with props
- Create Variants
- Extend components
- Add CSS Styles
- Use inside React components
- Add logic headers
- Recipes for
rc.extend
Make sure you have installed React (> 16.8.0) in your project.
npm i react-classmate
# or
yarn add react-classmateCreate a component by calling rc with a tag name and a template literal
string.
import rc from "react-classmate";
const Container = rc.div`
py-2
px-5
min-h-24
`;
// transforms to: <div className="py-2 px-5 min-h-24" />Additional Information: See "Base usage" documentation
Pass props to the component and use them in the template literal string and in the component prop validation.
// hey typescript
interface ButtonProps {
$isActive?: boolean;
$isLoading?: boolean;
}
const SomeButton = rc.button<ButtonProps>`
text-lg
mt-5
${(
p,
) => (p.$isActive ? "bg-blue-400 text-white" : "bg-blue-400 text-blue-200")}
${(p) => (p.$isLoading ? "opacity-90 pointer-events-none" : "")}
`;
// transforms to <button className="text-lg mt-5 bg-blue-400 text-white opacity-90 pointer-events-none" />we prefix the props incoming to dc with a $ sign. This is a important
convention to distinguish dynamic props from the ones we pass to the component.
This pattern should also avoid conflicts with reserved prop names.
Create variants by passing an object to the variants key like in
cva. The key should match the
prop name and the value should be a function that returns a string. You could
also re-use the props in the function.
interface AlertProps {
$severity: "info" | "warning" | "error";
$isActive?: boolean;
}
const Alert = rc.div.variants<AlertProps>({
// optional
base: (p) => `
${p.isActive ? "custom-active" : "custom-inactive"}
p-4
rounded-md
`,
// required
variants: {
$severity: {
warning: "bg-yellow-100 text-yellow-800",
info: (p) =>
`bg-blue-100 text-blue-800 ${p.$isActive ? "shadow-lg" : ""}`,
error: (p) =>
`bg-red-100 text-red-800 ${p.$isActive ? "ring ring-red-500" : ""}`,
},
},
// optional - used if no variant was found
defaultVariant: {
$severity: "info",
},
});
export default () => <Alert $severity="info" $isActive />;
// outputs: <div className="custom-active p-4 rounded-md bg-blue-100 text-blue-800 shadow-lg" />Additional Information: See "Variants" documentation
As seen above, we also pass AlertProps to the variants, which can cause loose
types. If you want to separate the base props from the variants, you can pass a
second type to the variants function so that only those props are available in
the variants.
interface AlertProps {
$isActive?: boolean;
}
interface AlertVariants {
$severity: "info" | "warning" | "error";
}
const Alert = rc.div.variants<AlertProps, AlertVariants>({
base: `p-4 rounded-md`,
variants: {
// in here there are only the keys from AlertVariants available
$severity: {
// you can use the props from AlertProps here again
warning: "bg-yellow-100 text-yellow-800",
info: (p) =>
`bg-blue-100 text-blue-800 ${p.$isActive ? "shadow-lg" : ""}`,
error: (p) =>
`bg-red-100 text-red-800 ${p.$isActive ? "ring ring-red-500" : ""}`,
},
},
// optional - used if no variant was found
defaultVariant: {
$severity: "info",
},
});Extend a component directly by passing the component and the tag name.
import MyOtherComponent from "./MyOtherComponent"; // () => <button className="text-lg mt-5" />
import rc from "react-classmate";
const Container = rc.extend(MyOtherComponent)`
py-2
px-5
min-h-24
`;
// transforms to: <button className="text-lg mt-5 py-2 px-5 min-h-24" />Additional Information: "Extend" documentation
You can use CSS styles in the template literal string with the style function.
This function takes an object with CSS properties and returns a string. We can
use the props from before.
// Base:
const StyledButton = rc.button<{ $isDisabled: boolean }>`
text-blue
${(p) =>
p.style({
boxShadow: "0 0 5px rgba(0, 0, 0, 0.1)",
cursor: p.$isDisabled ? "not-allowed" : "pointer",
})}
`;
export default () => <StyledButton $isDisabled />;
// outputs: <button className="text-blue" style="box-shadow: 0 0 5px rgba(0, 0, 0, 0.1); cursor: not-allowed;" />// Extended:
const BaseButton = rc.button<{ $isActive?: boolean }>`
${(p) =>
p.style({
backgroundColor: p.$isActive ? "green" : "red",
})}
`;
const ExtendedButton = rc.extend(BaseButton)<{ $isLoading?: boolean }>`
${(p) =>
p.style({
opacity: p.$isLoading ? 0.5 : 1,
pointerEvents: p.$isLoading ? "none" : "auto",
})}
`;
export default () => <ExtendedButton $isActive $isLoading />;
// outputs: <button className="bg-red" style="opacity: 0.5; pointer-events: none;" />When you need to create a classmate component inside another React component
(for example, when the configuration depends on runtime-only values), wrap the
factory with useClassmate. This memoizes the result and avoids creating a
brand-new component on every render.
import rc, { useClassmate } from "react-classmate";
const WorkoutDay = ({ status }: { status: "completed" | "pending" }) => {
const StyledDay = useClassmate(
() =>
rc.div.variants({
base: "rounded border p-4 text-sm",
variants: {
$status: {
completed: "border-green-400 bg-green-50",
pending: "border-yellow-400 bg-yellow-50",
},
},
}),
[status], // recompute when dependencies change
);
return <StyledDay $status={status}>Workout details</StyledDay>;
};The dependency array behaves like
React.useMemo. Pass everything the factory closes over if you expect the component to update when those values change.
Use .logic() to run arbitrary JavaScript once per render before your class
names or variants are computed. The return value is shallow-merged back into the
props, so you can derive $ props, DOM attributes, or anything else your
component needs without additional hooks.
type DayStatus = "completed" | "pending"
interface WorkoutProps {
workouts: unknown[]
allResolved: boolean
hasCompleted: boolean
hasSkipped: boolean
$status?: DayStatus
}
const WorkoutDay = rc.div
.logic<WorkoutProps>((props) => {
const status = deriveDayStatus(props)
return {
$status: status,
["data-status"]: status,
}
})
.variants<WorkoutProps, { $status: DayStatus }>({
base: "rounded border p-4",
variants: {
$status: {
completed: "bg-green-50 border-green-400",
pending: "bg-white border-slate-200",
},
},
})
// Consumers only pass raw workout data – the logic header derives $status for you.
<WorkoutDay workouts={workouts} allResolved hasCompleted hasSkipped={false} />Return values from
.logic()are merged in order, so later logic calls can reference earlier results or override them.
With rc.extend, you can build upon any base React component, adding new styles
and even supporting additional props. This makes it easy to create reusable
component variations without duplicating logic.
import { ArrowBigDown } from "lucide-react";
import rc from "react-classmate";
const StyledLucideArrow = rc.extend(ArrowBigDown)`
md:-right-4.5
right-1
slide-in-r-20
`;
// ts: we can pass only props which are accessible on a `lucid-react` Component
export default () => <StyledLucideArrow stroke="3" />;Now we can define a base component, extend it with additional styles and
classes, and pass properties. You can pass the types to the extend function to
get autocompletion and type checking.
import rc from "react-classmate";
interface StyledSliderItemBaseProps {
$active: boolean;
}
const StyledSliderItemBase = rc.button<StyledSliderItemBaseProps>`
absolute
h-full
w-full
left-0
top-0
${(p) => (p.$active ? "animate-in fade-in" : "animate-out fade-out")}
`;
interface NewStyledSliderItemProps extends StyledSliderItemBaseProps {
$secondBool: boolean;
}
const NewStyledSliderItemWithNewProps = rc.extend(
StyledSliderItemBase,
)<NewStyledSliderItemProps>`
rounded-lg
text-lg
${(p) => (p.$active ? "bg-blue" : "bg-red")}
${(p) => (p.$secondBool ? "text-underline" : "some-class-here")}
`;
export default () => (
<NewStyledSliderItemWithNewProps $active $secondBool={false} />
);
// outputs: <button className="absolute h-full w-full left-0 top-0 animate-in fade-in rounded-lg text-lg bg-blue" />const BaseButton = rc.extend(rc.button``)`
text-lg
mt-5
`;interface ButtonProps extends InputHTMLAttributes<HTMLInputElement> {
$severity: "info" | "warning" | "error";
$isActive?: boolean;
}
const Alert = rc.input.variants<ButtonProps>({
base: "p-4",
variants: {
$severity: {
info: (p) =>
`bg-blue-100 text-blue-800 ${p.$isActive ? "shadow-lg" : ""}`,
},
},
});
const ExtendedButton = rc.extend(Alert)<{ $test: boolean }>`
${(p) => (p.$test ? "bg-green-100 text-green-800" : "")}
`;
export default () => <ExtendedButton $severity="info" $test />;
// outputs: <input className="p-4 bg-blue-100 text-blue-800 shadow-lg bg-green-100 text-green-800" />By passing the component, we can validate the component to accept tag related
props. This is useful if you wanna rely on the props for a specific element
without the $ prefix.
// if you pass rc component it's types are validated
const ExtendedButton = rc.extend(rc.button``)`
some-class
${(p) => (p.type === "submit" ? "font-normal" : "font-bold")}
`;
// infers the type of the input element + add new props
const MyInput = ({ ...props }: HTMLAttributes<HTMLInputElement>) => (
<input {...props} />
);
const StyledDiv = rc.extend(MyInput)<{ $trigger?: boolean }>`
bg-white
${(p) => (p.$trigger ? "!border-error" : "")}
${(p) => (p.type === "submit" ? "font-normal" : "font-bold")}
`;Unfortunately we cannot infer the type directly of the component if it's any
or loosely typed. But we can use a intermediate step to pass the type to the
extend function.
import { ComponentProps } from 'react'
import { MapContainer } from 'react-leaflet'
import { Field, FieldConfig } from 'formik'
import rc, { RcBaseComponent } from 'react-classmate'
// we need to cast the type to ComponentProps
type StyledMapContainerType = ComponentProps<typeof MapContainer>
const StyledMapContainer: RcBaseComponent<StyledMapContainerType> = rc.extend(MapContainer)`
absolute
h-full
w-full
text-white
outline-0
`
export const Component = () => <StyledMapContainer bounds={...} />
// or with Formik
import { Field, FieldConfig } from 'formik'
type FieldComponentProps = ComponentProps<'input'> & FieldConfig
const FieldComponent = ({ ...props }: FieldComponentProps) => <Field {...props} />
const StyledField = rc.extend(FieldComponent)<{ $error: boolean }>`
theme-form-field
w-full
....
${p => (p.$error ? '!border-error' : '')}
`
export const Component = () => <StyledField placeholder="placeholder" as="select" name="name" $error />$error. Contributions welcome.
If you are using CommonJS, you can import the library like this:
const rc = require("react-classmate").default;
// or
const { default: rc } = require("react-classmate");React-classmate uses tailwind-merge under the hood to merge class names. The last class name will always win, so you can use it to override classes.
- bug / troubleshoot: classnames set by ref.current (useRef) will be overwritten
as soon component rerenders
- needs at least a small article in the docs
rc.raw()andrc.raw.variants()for only usingrcsyntax for classnames (output as string)- Variants for
rc.extend - named lib import for CommonJS (currently only
.default) -- Means we need to remove the named export in the ts file to not duplicate IDE import suggestions: --- Change postbuild script to remove named esm export - Integrate more tests, benchmarks focused on SSR and React
- Advanced IDE integration
- show generated default class on hover
- enforce autocompletion and tooltips from the used libs