Utility Types

Resolve<T>

Force TypeScript to eagerly evaluate a type, expanding conditional types and type aliases in IDE hover tooltips.

Problem

When hovering over a store’s $value in your IDE, TypeScript may show the unexpanded internal type:

ReadableAtom<InferValueFromSearchParamConfig<FallbackQueryParamConfig<DefaultQsRecord, BaseResult<boolean, boolean>>>>

Instead of the resolved type: ReadableAtom<boolean>.

Solution

import type { createQsUtils } from "@vp-tw/nanostores-qs";

// Wrap a type to force evaluation
type PageValue = createQsUtils.Resolve<ReturnType<typeof pageStore.$value.get>>;
// Hover: number

Usage

import type { createQsUtils } from "@vp-tw/nanostores-qs";

type Resolve<T> = createQsUtils.Resolve<T>;

// In your component types
interface Props {
  page: Resolve<ReturnType<typeof pageStore.$value.get>>;
  // Hover shows: number
  // Instead of: InferValueFromSearchParamConfig<...>
}

How it works

type Resolve<T> = T extends infer U ? U : never;

The T extends infer U ? U : never pattern forces TypeScript to resolve the type into a new type variable U, which triggers eager evaluation of any conditional types or type aliases that were deferred.

Limitations

• Does not always expand deeply nested types
• No runtime effect — purely a type-level tool
• Already applied internally where possible — most common cases don’t need manual wrapping

StoreConfig<T>

Type-safe config object for createSearchParamStore. See Custom Presets for details.

import type { createQsUtils } from "@vp-tw/nanostores-qs";

type MyConfig = createQsUtils.StoreConfig<{
  value: string;
  defaultValue: string;
  resolved: number;
}>;
// → { decode, defaultValue, encode?, resolve (required) }

Descriptor field	Effect
value	The decoded type ($value)
defaultValue	Default value type; omit for optional stores
resolved	The resolved type ($resolved); omit if same as value

When resolved ≠ value, the resolve function is required (not optional) — TypeScript will error if you forget it.

StoreConfigArray<T>

Same as StoreConfig but for isArray: true configs.

type MyArrayConfig = createQsUtils.StoreConfigArray<{
  value: number;
  resolved: string;
}>;
// → { isArray: true, decode, encode?, resolve (required) }