docs: add comments to shared.ts

packages/react/shared.ts

@@ -1,38 +1,91 @@
 import { twMerge } from "tailwind-merge";
 
+/**
+ * Takes a string, and returns boolean if it is "true" or "false".
+ * Otherwise, returns the string.
+ *
+ * @example
+ * ```
+ * type BooleanString = BooleanString<"true" | "false" | "other">
+ * // BooleanString = true | false | "other" = boolean | "other"
+ * ```
+ */
 type BooleanString<T extends string> = T extends "true"
   ? true
   : T extends "false"
     ? false
     : T;
 
-type RawVariantProps<V extends Record<string, Record<string, string>>> = {
-  [VariantKey in keyof V]?: BooleanString<keyof V[VariantKey] & string>;
+/**
+ * A type that represents a variant object.
+ *
+ * @example
+ * ```
+ * const variant: VariantType = {
+ *   opened: {
+ *     true: "opacity-100",
+ *     false: "opacity-0",
+ *   }
+ *   size: {
+ *     sm: "small",
+ *     md: "medium",
+ *     lg: "large",
+ *   },
+ *   color: {
+ *     red: "#ff0000",
+ *     green: "#00ff00",
+ *     blue: "#0000ff",
+ *   },
+ * }
+ * ```
+ */
+type VariantType = Record<string, Record<string, string>>;
+
+/**
+ * Takes VariantType, and returns a type that represents the variant object.
+ *
+ * @example
+ * ```
+ * type VariantKV = VariantKV<VariantType>
+ * // VariantKV = {
+ * //   opened: BooleanString<"true" | "false"> = boolean;
+ * //   size: BooleanString<"sm" | "md" | "lg">;
+ * //   color: BooleanString<"red" | "green" | "blue">;
+ * // }
+ * ```
+ */
+type VariantKV<V extends VariantType> = {
+  [VariantKey in keyof V]: BooleanString<keyof V[VariantKey] & string>;
 };
 
-export function vcn<V extends Record<string, Record<string, string>>>({
+export function vcn<V extends VariantType>({
   base,
   variants,
   defaults,
 }: {
   base?: string | undefined;
-  variants: V;
-  defaults: {
-    [VariantKey in keyof V]: BooleanString<keyof V[VariantKey] & string>;
-  };
+  variants: V /* VariantType */;
+  defaults: VariantKV<V>;
 }): [
-  (variantProps: RawVariantProps<V> & { className?: string }) => string,
+  (variantProps: Partial<VariantKV<V>> & { className?: string }) => string,
   <AnyPropBeforeResolve extends Record<string, any>>(
     anyProps: AnyPropBeforeResolve,
     options?: {
       excludeClassName?: boolean;
     }
   ) => [
-    RawVariantProps<V> & { className?: string },
-    Omit<AnyPropBeforeResolve, keyof RawVariantProps<V> | "className">,
+    Partial<VariantKV<V>> & { className?: string },
+    Omit<AnyPropBeforeResolve, keyof Partial<VariantKV<V>> | "className">,
   ],
 ] {
   return [
+    /**
+     * Takes any props (including className), and returns the class name.
+     * If there is no variant specified in props, then it will fallback to default.
+     *
+     * @param variantProps - The variant props including className.
+     * @returns The class name.
+     */
     ({ className, ...variantProps }) => {
       return twMerge(
         base,
@@ -41,13 +94,22 @@ export function vcn<V extends Record<string, Record<string, string>>>({
         ).map<string>(
           ([variantKey, defaultValue]) =>
             variants[variantKey][
-              (variantProps as unknown as RawVariantProps<V>)[variantKey] ??
+              (variantProps as unknown as Partial<VariantKV<V>>)[variantKey] ??
                 defaultValue
             ]
         ),
         className
       );
     },
+    /**
+     * Takes any props, parse variant props and other props.
+     * If `options.excludeClassName` is true, then it will parse className as "other" props.
+     * Otherwise, it will parse className as variant props.
+     *
+     * @param anyProps - Any props that have passed to the component.
+     * @param options - Options.
+     * @returns [variantProps, otherProps]
+     */
     (anyProps, options = {}) => {
       const variantKeys = Object.keys(variants) as (keyof V)[];
 
@@ -63,13 +125,27 @@ export function vcn<V extends Record<string, Record<string, string>>>({
         },
         [{}, {}]
       ) as [
-        RawVariantProps<V> & { className?: string },
-        Omit<typeof anyProps, keyof RawVariantProps<V> | "className">,
+        Partial<VariantKV<V>> & { className?: string },
+        Omit<typeof anyProps, keyof Partial<VariantKV<V>> | "className">,
       ];
     },
   ];
 }
 
+/**
+ * Extract the props type from return value of `vcn` function.
+ *
+ * @example
+ * ```
+ * const [variantProps, otherProps] = vcn({ ... })
+ * interface Props
+ *   extends VariantProps<typeof variantProps>, OtherProps { ... }
+ *
+ * function Component(props: Props) {
+ *   ...
+ * }
+ * ```
+ */
 export type VariantProps<F extends ReturnType<typeof vcn>[0]> = F extends (
   props: infer P
 ) => string