addClass: function (newClass) {
        this.elements.forEach((element, index) => {
            if (typeof newClass === 'function') {
                const cssClasses = newClass.call(element, index, element.className);
                $(element).addClass(cssClasses);
            }
        })
    }
    return this;
},

append: function (newChild) {
    if (typeof newChild == 'string') {
        if (this.elements.length > 1) {
            this.elements.forEach(element =>
                element.innerHTML = newChild);
        } else {
            this.elements[0].innerHTML = newChild;
        }

    } else {
        this.elements.forEach((element, index) => {
            if (newChild.hasOwnProperty('elements')) {
                element.appendChild(newChild.elements[0].cloneNode(true))
            } else {
                element.appendChild(newChild.cloneNode(true))
            }
        });

    }
    return this;
},
attr: function (attr, args) {
    if (arguments.length == 1) {
        return this.elements[0].getAttribute(attr);
    } else {
        this.elements.forEach(element => {
            for (let i = 0; i < arguments.length; i += 2) {
                element.setAttribute(arguments[i], arguments[i + 1]);
            }
        });
    }
    return this;
},
children : function () {
    if (typeof this.elements.length == 'undefined') {
        this.elements.children;
    }
    return this.elements[0].children;
};
html : function(arg) {
    if (!arg) return this.elements[0].innerHTML;
    if (typeof(arg) === "string") this.each(function (index, item) { item.innerHTML = arg; });
    if (typeof(arg) === "function") this.each(function (index, item) {item.innerHTML = arg(index); });
    return this;
};