Limit Function Calls to Once

/**
 * Creates a function that invokes `func`, with the `this` binding and arguments
 * of the created function, while it's called less than `n` times. Subsequent
 * calls to the created function return the result of the last `func`
 * invocation.
 *
 * @static
 *
 * @param {number} n The number of calls at which `func` is no longer invoked.
 * @param {Function} func The function to restrict.
 * @returns {Function} Returns the new restricted function.
 *
 * @example
 *
 * jQuery(element).on('click', before(5, addContactToList));
 * // => Allows adding up to 4 contacts to the list.
 *
 * @link https://lodash.com/docs/#before
 */
function before(n, func) {
    let result;

    if (typeof func !== "function") {
        throw new TypeError(
            "The second parameter (func) in before() must be a function."
        );
    }

    return function() {
        if (--n > 0) {
            result = func.apply(this, arguments);
        }

        if (n <= 1) {
            func = undefined;
        }

        return result;
    };
}

/**
 * Creates a function that is restricted to invoking `func` once. Repeat calls
 * to the function return the value of the first invocation. The `func` is
 * invoked with the `this` binding and arguments of the created function.
 *
 * @static
 *
 * @param {Function} func The function to restrict.
 * @returns {Function} Returns the new restricted function.
 *
 * @example
 *  var initialize = once(createApplication);
 *  initialize();
 *  initialize();
 *  // => `createApplication` is invoked once
 *
 * @link https://lodash.com/docs/#once
 */
function once(func) {
    return before(2, func);
}