manuthecoder-react-native-spotlight-tour/src/helpers/common.ts

React Native library to implement a highly customizable app tour feature with an awesome spotlight effect

import type { ReactNode } from "react";

/**
 * Like the built-in {@link Omit}, but constraints the target to extend from a
 * {@link Record} type. I.e., it's meant to be used with Records to omit
 * specified keys.
 */
export type OmitR<
  T extends Record<keyof unknown, unknown>,
  K extends keyof T,
> = Pick<T, Exclude<keyof T, K>>;

/**
 * Makes the target optional. I.e, it can be the target type or `undefined`.
 */
export type Optional<T> = T | undefined;

/**
 * Transforms the value types of an object to be `Optional`.
 */
export type ToOptional<T> = {
  [K in keyof Required<T>]: Optional<T[K]>;
};

/**
 * An alias of what a React child looks when passed as function.
 */
export type ChildFn<T> = (value: T) => ReactNode;

/**
 * Typeguard to check if any React children is represented as a function
 * instead of a Node. I,e., when it's a {@link ChildFn}.
 *
 * @param children any React children
 * @returns true if the children is a function, false otherwise
 */
export function isChildFunction<T>(children: ChildFn<T> | ReactNode): children is ChildFn<T> {
  return typeof children === "function";
}

/**
 * Typeguard to check if any value is a {@link Promise Promise\<T\>}. It allows
 * passing the generic param `T` to be explicit about the promise type.
 *
 * @param value any value to check against the guard
 * @returns true if the value is a Promise<T>, false otherwise.
 */
export function isPromise<T>(value?: unknown): value is Promise<T> {
  const maybePromise = value as Promise<T>;

  return typeof value === "object"
    && value !== null
    && typeof maybePromise.then === "function"
    && typeof maybePromise.catch === "function"
    && typeof maybePromise.finally === "function";
}