javascript - 使用 JavaScript 滚动时如何将左侧菜单设置为粘性

Question

我刚刚使用左侧固定的导航栏创建了一组复选框。我希望这个菜单像粘性一样。这怎么可能。

var acc = document.getElementsByClassName("accord");
var i;

for (i = 0; i < acc.length; i++) {
    acc[i].onclick = function(){
        var panel = this.nextElementSibling;
        if (panel.style.display === "none") {
            panel.style.display = "block";
        } else {
            panel.style.display = "none";
        }
    }
}
  

*{
    padding: 0;
    margin: 0;
}
.navbar-fixed-left{
    background-color: #fff;
    border-radius: 0;
    border-color: transparent;
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    box-shadow: 0px 0px 4px 1px rgba(0,0,0,0.14);
}
.panel-heading{
    background-color: transparent !important;
    padding: 10px 15px 10px 25px;
}
.panel-group{
    margin-top: 10px;
}
.panel{
    border: none;
    border-radius: 0;
}
.panel-body{
    border: none !important;
    padding: 15px 15px 15px 25px;
}
.catg-lists{
    padding-left: 10px;
    padding-bottom: 18px;
}
.catg-lists li{
    list-style-type: none;
    margin-bottom: 4px;
    color: #838383;
    font-size: 16px;
    text-transform: capitalize;
}
.catg-lists li input[type=checkbox]{
    margin-right: 6px;
}
.cat-menu{
    padding: 8px 15px 8px 4px;
    border-bottom: 2px solid #359443;
}
.cat-menu span{
    text-transform: capitalize;
    font-size: 15px; 
    font-weight: 600;
    color: #292929;
    padding: 2px 20px 6px 5px;
    border-bottom: 2px solid #458b53;
}
.cat-menu:hover, .cat-menu:active, .cat-menu:visited, .cat-menu:focus{
    text-decoration: none;
}
.accord {
    display: block;
    color: #444;
    cursor: pointer;
    padding: 18px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 15px;
    transition: 0.4s;
    position: relative;
}
.accord i{
    position: absolute;
    right: 30px;
    top: 22px;
    color: #349342;
}
div.panel {
    padding: 0 18px;
    background-color: white;
}

<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">

<section id="photo-gall">
            <div class="container">
                <div class="row">
                    <div class="col-xs-12 col-sm-4">
                        <div class="navbar navbar-inverse navbar-fixed-left">
                            <div class="panel-group" id="accordion">
                                <a class="cat-menu accord">
                                    <span>category</span><i class="fa fa-caret-down"></i></a> 
                                <div class="panel">
                                    <ul class="catg-lists">
                                        <li><input type="checkbox">fruits & vegetables</li>   
                                        <li><input type="checkbox">fresh fruits <span>(87)</span></li>
                                        <li><input type="checkbox">fresh vegetables <span>(191)</span></li>
                                        <li><input type="checkbox">international fruits & vegetables <span>(128)</span></li>
                                        <li><input type="checkbox">organic fruits & vegetables <span>(50)</span></li>
                                    </ul>
                                </div>

                                <a class="cat-menu accord">
                                    <span>price</span><i class="fa fa-caret-down" ></i></a> 
                                <div class="panel">
                                    <ul class="catg-lists">
                                        <li><input type="checkbox">Less than rs 20 <span>(53)</span></li>   
                                        <li><input type="checkbox">rs 21 to rs 50 <span>(164)</span></li>
                                        <li><input type="checkbox">rs 51 to rs 100<span>(126)</span></li>
                                        <li><input type="checkbox">rs 101 to rs 200 <span>(77)</span></li>
                                        <li><input type="checkbox">rs 201 to rs 500 <span>(62)</span></li>
                                        <li><input type="checkbox">more than rs 501 <span>(27)</span></li>
                                    </ul>
                                </div>

                                <a class="cat-menu accord">
                                    <span>pack size</span><i class="fa fa-caret-down" ></i></a> 
                                <div class="panel">
                                    <ul class="catg-lists">
                                        <li><input type="checkbox">100 grams <span>(53)</span></li>   
                                        <li><input type="checkbox">200 grams <span>(164)</span></li>
                                        <li><input type="checkbox">300 grams<span>(126)</span></li>
                                        <li><input type="checkbox">500 grams <span>(77)</span></li>
                                        <li><input type="checkbox">750 grams <span>(62)</span></li>
                                        <li><input type="checkbox">1 Kg <span>(27)</span></li>
                                        <li><input type="checkbox">2 Kg <span>(43)</span></li>
                                        <li><input type="checkbox">combo - 2 items<span>(0)</span></li>
                                        <li><input type="checkbox">combo - 3 items<span>(50)</span></li>
                                        <li><input type="checkbox">combo - 4 items<span>(10)</span></li>
                                    </ul>
                                </div>

                                <a class="cat-menu accord">
                                    <span>discounts</span><i class="fa fa-caret-down" ></i></a> 
                                <div class="panel">
                                    <ul class="catg-lists">
                                        <li><input type="checkbox">10%-20%</li>   
                                        <li><input type="checkbox">30%-40%</li>
                                        <li><input type="checkbox">50%</li>
                                        <li><input type="checkbox">60%-70%</li>
                                        <li><input type="checkbox">80%-90%</li>
                                    </ul>
                                </div>
                            </div>
                        </div>
                    </div>
                    
                    <div class="col-xs-12 col-sm-8">
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                        <h1>Some content</h1>
                    </div>
                </div> 
            </div>
        </section>

当我滚动页面时，菜单应该具有粘性。我试过了，但没有用。

注意:在宽屏幕上检查此代码以获得更好的结果。可能会在片段中混淆。

这是这段代码的结果。

如何实现粘性菜单？

提前致谢。

Answer 1

您需要使用固定位置并将其添加到滚动:

添加 jQuery:

<script
  src="https://code.jquery.com/jquery-2.2.4.min.js"
  integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44="
  crossorigin="anonymous"></script>

为固定位置和最大宽度添加 CSS 类，否则 width:100% + position: fixed 元素将占据窗口全宽。注意 left:auto 当它固定时，否则 left:0 它将一直向左移动:

.navbar-fixed-left{
    background-color: #fff;
    border-radius: 0;
    border-color: transparent;
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    max-width: 350px;
    box-shadow: 0px 0px 4px 1px rgba(0,0,0,0.14);
}
.navbar-fixed-left.fixed{
  position: fixed;
  top:0;
  left: auto;
}

添加JS检测滚动页面并添加类:

var $sidebar = jQuery('.navbar-fixed-left'),
    $window = jQuery(window),
    offset = $sidebar.offset();
$window.scroll(function() {
    if ($window.scrollTop() > offset.top) {
        $sidebar.addClass('fixed');
    } else {
        $sidebar.removeClass('fixed');
    }
});