问为什么当我使用原型时，我的Modal代码会失败，而当我使用"this“(Vanilla JS)时，我的Modal代码会失败呢？

EN

(function() {
    /**
     * Creates a Modal dialog. The user should call `removeModal` when they are
     * finished using it.
     * @param {boolean} defaultShow whether or not the modal is shown by default
     * @param {HTMLElement} bodyContent the body of the modal
     * @param {HTMLButtonElement | undefined} footerContent footer of the modal
     */
    function Modal(defaultShow, initialBodyContent, initialFooterContent) {
        let isActive = false;

        // Create the modal and append it to the dom
        let containerElement = document.createElement("div");
        containerElement.className = "modal-container";
        containerElement.id = Math.random().toString();

        let modalBody = document.createElement("div");
        modalBody.className = "modal-body";
        if (initialBodyContent) {
            modalBody.appendChild(initialBodyContent);
        }
        containerElement.appendChild(modalBody);

        let modalFooter = document.createElement("div");
        modalFooter.className = "modal-footer";
        if (initialFooterContent) {
            modalFooter.appendChild(initialFooterContent);
        }

        containerElement.appendChild(modalFooter);
        document.body.appendChild(containerElement);

        /**
         * Shows the modal with new content, optionally
         * @param {HTMLElement | undefined} newBodyContent replacement body element
         * @param {HTMLElement | undefined} newFooterContent replacement footer element
         */
        function showModal(newBodyContent, newFooterContent) {
            if (isActive) {
                return;
            }

            if (newBodyContent) {
                modalBody.innerHTML = "";
                modalBody.appendChild(newBodyContent);
            }

            if (newFooterContent) {
                modalFooter.innerHTML = "";
                modalFooter.appendChild(newFooterContent);
            }

            isActive = true;
            containerElement.classList.add("show");
            containerElement.classList.remove("hide");
        }

        /**
         * Hides the modal, but does not delete it from the DOM
         */
        function hideModal() {
            isActive = false;
            containerElement.classList.add("hide");
            containerElement.classList.remove("show");
        }

        /**
         * Completely removes the modal from the DOM
         */
        function removeModal() {
            $(containerElement).remove();
        }

        Modal.prototype.showModal = showModal;
        Modal.prototype.hideModal = hideModal;
        Modal.prototype.removeModal = removeModal;
        Modal.prototype.isShowing = function() { return isActive; };

        if (defaultShow) {
            showModal();
        } else {
            hideModal();
        }
    }
    
    module.exports = { Modal: Modal };
}())

const myModal1 = new Modal(false);
const myModal2 = new Modal(false);

function Modal() {
    ....
    this.showModal = showModal;
    this.hideModal = hideModal;
    etc...
    ...
}