window.$ = function (selectorOrElement) {

            var elements;
            if (typeof selectorOrElement === "string") {
                elements = document.querySelectorAll(selectorOrElement);//伪数组，有length对象
            } else if (selectorOrElement instanceof Element) {
                elements = { 0: selectorOrElement, length: 1 };//假数组
            } else if (selectorOrElement instanceof Array) {
                elements = {};
                for (var i = 0; i < selectorOrElement.length; i++) {
                    elements[i] = selectorOrElement[i];
                }
                elements.length = selectorOrElement.length;
            }

            //添加事件
            elements.on = function (eventType, fn) {
                for (var i = 0; i < elements.length; i++) {
                    var element = elements[i];
                    if (element.addEventListener) {
                        element.addEventListener(eventType, fn);
                    } else if (element.attachEvent) {
                        element.attachEvent('on' + eventType, fn);
                    }
                }
                return elements;
            };
            //添加类
            elements.addClass = function (className) {
                for (var i = 0; elements.length; i++) {
                    if (elements[i].classList) {//其它浏览器
                        elements[i].classList.add(className);
                    } else {//IE
                        elements[i].className = elements[i].className + ' ' + className;
                    }
                }
                return elements;
            };
            //移除类
            elements.removeClass = function (className) {
                for (var i = 0; i < elements.length; i++) {
                    if (elements[i].classList) {//其它浏览器
                        elements[i].classList.remove(className);
                    } else {/*IE需要正则表达式，暂时不会*/ }
                }
                return elements;
            };
            //设置内容
            elements.text = function (string) {
                if (arguments.length === 0) {//string===undefined
                    let result = [];
                    for (let i = 0; i < elements.length; i++) {
                        if (elements[i].textContent !== undefined) {
                            result.push(elements[i].textContent);
                        } else if (elements[i].innerText !== undefined) {
                            result.push(elements[i].innerText);
                        }
                    }
                    return result;
                } else {
                    for (let i = 0; i < elements.length; i++) {
                        if (elements[i].textContent !== undefined) {//w3c
                            elements[i].textContent = string;
                        } else if (elements[i], innerText !== undefined) {//IE
                            elements[i].innerText = string;
                        }
                    }
                    return elements;
                }
            };
            //设置html
            elements.html = function (string) {
                if (arguments.length === 0) {//string===undefined
                    let result = [];
                    for (let i = 0; i < elements.length; i++) {
                        result.push(elements[i].innerHTML);
                    }
                    return result;
                } else {
                    for (let i = 0; i < elements.length; i++) {
                        elements[i].innerHTML = string;
                    }
                    return elements;
                }
            };

            //获取指定索引成员
            elements.get = function (index) {

                return elements[index];
            };
            //获取所有元素的所有兄弟
            elements.siblings = function () {
                var result = [];
                for (var i = 0; i < elements.length; i++) {
                    var element = elements[i];
                    var children = element.parentNode.children;
                    for (var j = 0; j < children.length; j++) {
                        if (children !== element) {
                            result.push(children[j]);
                        }
                    }
                }
                var objectResult = $(result);
                return objectResult;
            };
            //返回伪数组对象
            return elements;
        };


        var items = $('li');


        items.on('click', function () {
            console.log('click');
        });


        items.on('dblclick', function () {
            console.log('双击');
            items.addClass('active');
        });

        //items.text("ww");
        //console.log(items.text());
        //console.log(items.html('<p>aa</p>'));
        items[0].style.border = "1px solid";
        items.get(1).style.border = '1px solid blue';

        var item = $(items[2]);

        console.log(items.siblings());
        item.siblings().addClass('active');
    </script>