defineConfig

defineConfig creates a custom set of cva, cx, and compose functions bound to a shared configuration. The primary use case is attaching an onComplete hook — most commonly to pipe the final class string through tailwind-merge.

Signature

import { defineConfig } from "cva";

interface DefineConfig {
  (options?: DefineConfigOptions): {
    compose: Compose;
    cx: CX;
    cva: CVA;
  };
}

interface DefineConfigOptions {
  hooks?: {
    /** Returns the completed string of concatenated classes/classNames. */
    onComplete?: (className: string) => string;
    /**
     * @deprecated Use `onComplete` instead.
     */
    "cx:done"?: (className: string) => string;
  };
}

Parameters

DefineConfigOptions

Optional configuration object.

Show options

object

Lifecycle hooks.

Show hooks

(className: string) => string

Called with the fully concatenated class string after every cva, cx, or compose call. The return value replaces the class string.This is the recommended hook for integrating tailwind-merge or any other post-processing step.

(className: string) => string

deprecated

Deprecated alias for onComplete. Use onComplete instead.

cx:done is deprecated and may be removed in a future release. Migrate to onComplete.

Return value

CVA

A cva function bound to the provided config. Equivalent to the named export from cva, but runs every resolved class string through the onComplete hook.

A cx function bound to the provided config. Equivalent to clsx, but runs its output through the onComplete hook.

Compose

A compose function bound to the provided config. Equivalent to the named export from cva, but runs the final concatenated string through the onComplete hook.

Tailwind-merge integration

The recommended pattern is to call defineConfig once in a shared utility module and re-export the results. All components that import from that module get tailwind-merge conflict resolution for free.

lib/utils.ts

import { defineConfig } from "cva";
import { twMerge } from "tailwind-merge";

export const { cva, cx, compose } = defineConfig({
  hooks: {
    onComplete: (className) => twMerge(className),
  },
});

Then import from your local module instead of from cva directly:

components/button.ts

import { cva, type VariantProps } from "../lib/utils";

const button = cva({
  base: ["font-semibold", "border", "rounded"],
  variants: {
    intent: {
      primary: ["bg-blue-500", "text-white", "border-transparent"],
      secondary: ["bg-white", "text-gray-800", "border-gray-400"],
    },
  },
  defaultVariants: { intent: "primary" },
});

export type ButtonProps = VariantProps<typeof button>;

Because defineConfig wires the hook into cx and compose as well, all three functions benefit from conflict resolution without any additional setup.

For a full walkthrough of Tailwind CSS setup — including IntelliSense and the Prettier plugin — see the Tailwind CSS guide.

​defineConfig

​Signature

​Parameters

​Return value

​Tailwind-merge integration

defineConfig

Signature

Parameters

Return value

Tailwind-merge integration