Js实现京东无延迟菜单效果(demo) 慕课网

时间：2022-11-21 07:45:44
先来理清思路:1.开发基本的菜单结构     

2.开发普通的二级菜单效果

3.假如延迟解决移动问题

  切换子菜单时候，用setTimeout设置延迟

  debounce去抖技

  在事件被频繁触发是，只执行一次处理

4.解决延迟引入的新问题

  跟踪鼠标的移动

  用鼠标当前位置，和鼠标上一次位置与子菜单上下边缘的三角形区域进行比较

  运用到向量

  二位向量叉乘公式

  用叉乘法判断点在三角形内
最终效果：鼠标自然的移动和点击到子菜单

         切换时无延迟

下面开始代码：

开发基本的菜单结构

<!doctype html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>京东菜单无刷新</title>

    <script src="js/jquery-1.7.2.min.js"></script>

    <script src="js/mche.js"></script>

    <script src="js/function.js"></script>

    <style>

        .wrap{

            position:relative;

            width:200px;

            left:50px;

            top:50px;

        }

        ul{

            padding:15px;

            margin:;

            list-style:none;

            background:#6c6669;

            color:#ffffff;

            border-right-width:;

        }

        /*水平居中*/

        li{

            display:block;

            height:30px;

            line-height: 30px;

            padding-left:12px;

            cursor:pointer;

            font-size: 14px;

            position:relative;

        }

        /*鼠标移动上去的背景色*/

        li.active{

            background:#999395;

        }

        /*js可以很好地调用类，一般效果css实现就好*/

        li span:hover{

            color:#c81623;

        }

        /*隐藏的类*/

        .none{

            display: none;

        }

        /*二级菜单*/

        #sub{

            width:600px;

            position: absolute;

            border:1px solid #f7f7f7;

            background:#f7f7f7;

            box-shadow:2px 0 rgba(0,0,0,.3);

            left: 200px;

            top:;

            box-sizing:border-box;

            margin: 0px;

            padding:10px;

        }

        .sub-content a{

            font-style:12px;

            color:#666;

            text-decoration:none;

        }

        .sub-content dd a{

            border-left:1px solid #e0e0e0;

            padding:0 1px;

            margin:4px 0;

        }

        .sub-content dl {

            overflow:hidden;

        }

        .sub-content dt{

            float: left;

            width:70px;

            font-weight: bold;

            clear:left;

            position:relative;

        }

        .sub-content dd {

            float: left;

            margin-left: 5px;

            border-top:1px solid #eee;

            margin-bottom: 5px;

        }

        .sub-content dt i{

            width:4px;

            height: 14px;

            font:400 9px/14px consolas;

            position: absolute;

            right:5px;

            top:5px;

        }

    </style>

</head>

<body>

<div class="wrap" id="test">

<ul>

    <li data-id="a">

    <span>家用电器</span>

    </li>

    <li data-id="b">

    <span>手机 / 运营商 / 数码</span>

    </li>

    <li data-id="c">

    <span>电脑办公 / 办公</span>

    </li>

    <li data-id="d">

    <span>家居 / 家具 / 家装 / 厨具</span>

    </li>

    <li data-id="e">

    <span>男装 / 女装 / 童装 / 内衣 </span>

    </li>

    <li data-id="f">

    <span>美妆个护 / 宠物 </span>

    </li>

    <li data-id="g">

    <span>女鞋 / 箱包 / 钟表 / 珠宝 </span>

    </li>

    <li data-id="h">

    <span>男鞋 / 运动 / 户外</span>

    </li>

    <li data-id="i">

    <span>汽车 / 汽车用品  </span>

    </li>

</ul>

    <div id="sub" class="none">

        <div id="a" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">电视<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">曲面电视</a>

                    <a href="#">超薄电视</a>

                    <a href="#">HDR电视</a>

                    <a href="#">DLED电视</a>

                </dd>

                <dt>

                    <a href="#">空调<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">挂壁式空调</a>

                    <a href="#">柜式空调</a>

                    <a href="#">*空调</a>

                    <a href="#">以旧换新</a>

                </dd>

                <dt>

                    <a href="#">洗衣机<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">滚筒式洗衣机</a>

                    <a href="#">洗烘一体机</a>

                    <a href="#">波轮洗衣机</a>

                    <a href="#">迷你洗衣机</a>

                </dd>

            </dl>

        </div>

        <div id="b" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">手机通讯<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">手机</a>

                    <a href="#">对讲机</a>

                    <a href="#">以旧换新</a>

                    <a href="#">手机维修</a>

                </dd>

                <dt>

                    <a href="#">运营商<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">合约机</a>

                    <a href="#">选号机</a>

                    <a href="#">固定电话</a>

                    <a href="#">办宽带</a>

                </dd>

                <dt>

                    <a href="#">手机配件<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">手机壳</a>

                    <a href="#">贴膜</a>

                    <a href="#">手机存储卡</a>

                    <a href="#">数据线</a>

                </dd>

            </dl>

        </div>

        <div id="c" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">电脑整机<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">笔记本</a>

                    <a href="#">游戏本</a>

                    <a href="#">平板电脑</a>

                </dd>

                <dt>

                    <a href="#">电脑配件<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">显示器</a>

                    <a href="#">CPU</a>

                    <a href="#">主板</a>

                </dd>

                <dt>

                    <a href="#">外设产品<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">鼠标</a>

                    <a href="#">键盘</a>

                    <a href="#">键盘套餐</a>

                </dd>

            </dl>

        </div>

        <div id="d" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">厨具<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">烹饪锅具</a>

                    <a href="#">刀剪配件</a>

                    <a href="#">厨房配件</a>

                    <a href="#">水具酒具</a>

                </dd>

                <dt>

                    <a href="#">家纺<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">床品套件</a>

                    <a href="#">被子</a>

                    <a href="#">枕芯</a>

                    <a href="#">蚊帐</a>

                </dd>

                <dt>

                    <a href="#">生活日用<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">收纳用品</a>

                    <a href="#">雨伞雨具</a>

                    <a href="#">净化除味</a>

                    <a href="#">浴室用品</a>

                </dd>

            </dl>

        </div>

        <div id="e" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">女装<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">商城同款</a>

                    <a href="#">当季热卖</a>

                    <a href="#">2017新品</a>

                    <a href="#">连衣裙</a>

                </dd>

                <dt>

                    <a href="#">男装<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">商城同款</a>

                    <a href="#">当季热卖</a>

                    <a href="#">2017新品</a>

                    <a href="#">牛仔裤</a>

                </dd>

            </dl>

        </div>

        <div id="f" class="sub-content none">

            <dl>

                <dt>

                    <a href="#">面部护肤<i>&gt</i></a>

                </dt>

                <dd>

                    <a href="#">补水保湿</a>

                    <a href="#">卸妆</a>

                    <a href="#">洁面</a>

                </dd>

            </dl>

        </div>

    </div>

</ul>

</body>

</html>

解决第2、3个问题

$(document).ready(function(){

    var sub = $('#sub')

    var activeRow

    var activeMenu

    var timer

    var mouseInSub = false

    sub.on('mouseenter',function(e){

        mouseInSub = true

    }).on('mouseleave',function(e){

        mouseInSub = false

    })

    var mouseTrack = []

    var moveHandler = function(e){

        mouseTrack.push({

            x:e.pageX,

            y:e.pageY

        })

        if(mouseTrack.length > 3){

            mouseTrack.shift()

        }

    }

    $('#test')

        .on('mouseenter',function(e){

            sub.removeClass('none')

            $(document).bind('mousemove',moveHandler)

        })

        .on('mouseleave',function(e){

            sub.addClass('none')

            if(activeRow){

                activeRow.removeClass('active')

                activeRow = null;

            }

            if(activeMenu){

                activeMenu.addClass('none')

                activeMenu = null;

            }

            //解绑

            $(document).unbind('mousemove',moveHandler)

        })

        .on('mouseenter','li',function(e){

            if(!activeRow){

                activeRow = $(e.target).addClass('acrive')

                activeMenu = $('#'+activeRow.data('id'))

                activeMenu.removeClass('none')

                return

            }

            //清除

            if(timer){

                clearTimeout(timer)

            }

            //鼠标当前坐标

            var  currMousePos = mouseTrack[mouseTrack.length - 1]

            //上次的坐标

            var leftCorner = mouseTrack[mouseTrack.length-2]

            var delay = needDelay(sub,leftCorner,currMousePos)

            if(delay){

                // 时间触发，设置一个缓冲期

                timer = setTimeout(function(){

                    //判断

                    if(mouseInSub){

                        return

                    }

                    activeRow.removeClass('active')

                    activeMenu.addClass('none')

                    activeRow = $(e.target)

                    activeRow.addClass('active')

                    activeMenu = $('#'+ activeRow.data('id'))

                    activeMenu.removeClass('none')

                    timer = null

                }, 300)

            }else{

                var prevActiveRow = activeRow

                var prevActiveMenu = activeMenu

                activeRow = $(e.target)

                activeMenu = $('#' + activeRow.data('id'))

                prevActiveRow.removeClass('active')

                prevActiveMenu.addClass('none')

                activeRow.addClass('active')

                activeMenu.removeClass('none')

            }

        })

})

解决延迟引入的新问题

function sameSign(a,b){

    return (a ^ b) >= 0

}

function vector(a,b){

    return{

        x:b.x - a.x,

        y:b.y - a.y

    }

}

function vectorProduct(v1,v2){

    return v1.x * v2.y - v2.x * v1.y

}

function isPointInTrangle(p,a,b,c){

    var pa = vector(p,a)

    var pb = vector(p,b)

    var pc = vector(p,c)

    var t1 = vectorProduct(pa,pb)

    var t2 = vectorProduct(pb,pc)

    var t3 = vectorProduct(pc,pa)

    return sameSign(t1,t2) && sameSign(t2,t3)

} 

function needDelay(elem,leftCorner,currMousePos){

    var offset = elem.offset()

    var topLeft = {

        x:offset.left,

        y:offset.top

    }

    var bottomLeft = {

        x:offset.left,

        y:offset.top + elem.height()

    }

    return isPointInTrangle(currMousePos,leftCorner,topLeft,bottomLeft)

}

Js实现京东无延迟菜单效果(demo) 慕课网

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