Function lazy

frontend/util/util.ts:250–259

(callback: T)

 * @returns The result of the function.
 */
const lazy = <T extends (...args: any[]) => any>(callback: T) => {
    let res: ReturnType<T>;
    let processed = false;
    return (...args: Parameters<T>): ReturnType<T> => {
        if (processed) return res;
        res = callback(...args);
        processed = true;
        return res;
    };
};

/**
 * Generates an external link by appending the given URL to the "https://extern?" endpoint.