/**
 * Normalize a single value or array into an array.
 * Avoids repeated Array.isArray checks throughout the codebase.
 *
 * @example
 *     toArray('a');       // ['a']
 *     toArray(['a','b']); // ['a','b']
 */
export declare function toArray<T>(value: T | T[]): T[];
/**
 * Check if a CSS property is a custom property (--*).
 * Custom properties use `setProperty`/`getPropertyValue` instead of
 * direct style access, so we need to distinguish them.
 *
 * @example
 *     isCustomProp('--color');  // true
 *     isCustomProp('color');    // false
 */
export declare function isCustomProp(name: string): name is `--${string}`;
/**
 * Apply a callback to each combination of elements and keys.
 * Eliminates the repeated `toArray(els) → for el → for key → action` pattern.
 *
 * @example
 *     eachEl(els, keys, (el, key) => el.removeAttribute(key));
 */
export declare function eachEl<E, K>(els: E | E[], keys: K | K[], fn: (el: E, key: K) => void): void;
/**
 * Apply a callback to each element in a OneOrMany.
 * Single-key variant of eachEl for set-all / hide / show patterns.
 *
 * @example
 *     applyEach(els, el => el.setAttribute('aria-hidden', 'true'));
 */
export declare function applyEach<E>(els: E | E[], fn: (el: E) => void): void;
/**
 * Get multiple values from a single element, returning a Record.
 * Eliminates repeated "for key → result[key] = getter(key)" pattern.
 *
 * @example
 *     getMany(el, ['role', 'id'], name => el.getAttribute(name));
 */
export declare function getMany<V>(keys: string[], getter: (key: string) => V): Record<string, V>;
/**
 * Wire an AbortSignal to a stop/cleanup function.
 * Eliminates the repeated `signal.addEventListener('abort', stop, { once: true })` pattern.
 *
 * @example
 *     bindSignal(opts?.signal, stop);
 */
export declare function bindSignal(signal: AbortSignal | undefined, stop: () => void): void;