jQuery實現頁面導航內容定位效果，並支持內容切換

需求

頁面向下滾動時，需要將頂部的搜索欄信息和導航菜單吸頂，並且，搜索欄信息和導航菜單之間可以切換。

效果

https://www.iguopin.com/index.php?m=&c=index&a=index

代碼實現

HTML

	<div class="nav-search">
		<div class="container">
			<div class="navbar-header">
				<a class="navbar-brand" href="#">
					<img alt="Brand" src="../public/images/igplogo2.png" class="header-brand">
				</a>
			</div>
			<div class="right_part  noprint">
				<form class="ip-group">
					<div class="ip-box">
						<div class="type">
							<div class="text"></div>
							<i class="layui-icon layui-icon-down" style="font-size: 18px;cursor: pointer;"></i>
							<div class="dpdown">
								<div class="option" id="1">社會招聘</div>
								<div class="option" id="2">校園招聘</div>
								<div class="option" id="3">高端職位</div>
								<div class="option" id="4">實習職位</div>
							</div>
						</div>
						<input
							type="text"
							name="jobkey"
							id="top_search_input"
							value=""
							placeholder="請輸入職位或企業名稱"/>
					</div>
					<input type="submit" class="ip-btn" value="搜索">
					<input type="hidden" name="act" id="top_search_type" value="QS_jobslist"/>
				</form>
				<div class="nav-btn">
					<span class="nav-text">導航</span>
					<span class="iconfont icon-other"></span>
				</div>
				<div class="qrcodes">
					<img class="qrcode qr1" src="../public/images/index/gp_qrcode.png"></img>
					<img class="qrcode qr2" src="../public/images/index/gpfb_qrcode.png"></img>
					<div class="qrcode-tip-box">
						<span class="tip1 active">關注最新招聘資訊</span>
						<span class="tip2">獲取簡歷投遞狀態</span>
					</div>
				</div>
				<div class="clear"></div>
			</div>
		</div>
	</div>
...
...
...
<div class="link-nav">
  <div class="container">
    <ul class="nav navbar-nav site_link">
      <li><a target="_blank" href="www.iguopin.com">國聘行動</a></li>
      <li><a target="_blank" href="https://zhaogong.iguopin.com/">線上招工</a></li>
      <li><a target="_blank" href="https://zhaogong.iguopin.com/abroad">一帶一路</a></li>
    </ul>
    <div class="clearfix"></div>
  </div>
</div>

css

.nav-search {
	width: 100%;
	background-color: #fff;
	z-index: 1000;
}
.navbar .container .navbar-header {
    margin-right: 0;
    float: none;
    margin-left: 0;
    width: 20%;
}
.navbar .container .right_part {
	align-items: center;
    width: 80%;
}
.nav-btn {
	float: right;
	display: none;
	width: 70px;
	margin-left: 40px;
	font-size: 16px;
	color: #c90808;
	line-height: 85px;
	cursor: pointer;
}
.nav-search-fixed {
	position: fixed;
	top: 0;
	-webkit-box-shadow: 2px 2px 10px #ccc;
    box-shadow: 2px 2px 10px #ccc;
}
.nav-search-fixed .navbar-header {
	display: none;
}
.navbar .nav-search-fixed .container .right_part {
	width: 100%;
}
.navbar .nav-search-fixed .container .right_part .ip-group {
	margin-left: 100px;
}
.nav-search-fixed .nav-btn {
	display: inline-block;
	position: relative;
    top: 2px;
}
...
...
...
.link-nav {
  width: 100%;
  border-bottom: 2px solid #c90808;
  background: #fff;
  box-sizing: border-box;
  height: 72px;
  .container {
    width: 1200px;
    margin: 0 auto;
    height: 72px;
    box-sizing: border-box;

    .navbar-nav {
      width: 100%;
      height: 72px;
      display: -webkit-box;
      display: -ms-flexbox;
      display: flex;
      -ms-flex-pack: distribute;
      justify-content: space-around;
      -webkit-box-align: center;
      -ms-flex-align: center;
      align-items: center;
      margin: 0;
      padding: 0;
      list-style: none;

      > li {
        float: left;
        position: relative;
        display: block;
        padding: 0;
        margin: 0;
        line-height: 72px;
        list-style-type: none;
        box-sizing: border-box;
       }
      }

      > .avatar-li {
        &:hover {
          .dropdown-menu {
            display: block;
          }
        }
       }
      }
    }
  }
  .container-fixed {
    position: fixed;
    z-index: 1000;
    width: 1070px;
    top: 0;
    .navbar-nav {
      height: 120px;
    line-height: 120px;
    > li {
      line-height: 120px;
      &.active, &:hover {
        height: 120px;
      }
    }
    }
  }
  .clearfix {
    zoom: 1;
    display: block;
  }
}
.link-nav-fixed {
  width: 1200px;
  margin: 0 auto;
}

JS

        $(function () {
            // 導航吸頂
            fixedNav();
            $(window).scroll(function () {
                fixedNav();
            })
        });
        // 頁面滾動到一定高度，固定頂部導航
        var flag = false;
        function fixedNav() {
            var top = $(document).scrollTop();
            if (top >= 212) {
                $('.nav-search').addClass('nav-search-fixed');
                navChange();
            } else {
                $('.nav-search').removeClass('nav-search-fixed');
                $('.ip-group').show();
                $('.qrcodes').show();
                $('.container').removeClass('container-fixed');
                $('.link-nav').removeClass('link-nav-fixed');
            }
        };
        // 定位導航內容切換
        $('.nav-btn').click(function () {
            flag = !flag;
            navChange();
        });
        function navChange() {
            if (flag) {
                $('.nav-text').text("搜索");
                $('.nav-btn').children('.iconfont').removeClass('icon-other').addClass('icon-search');
                $('.ip-group').hide();
                $('.qrcodes').hide();
                $('.link-nav').addClass('link-nav-fixed');
                $('.container').addClass('container-fixed');
            } else {
                $('.nav-text').text("導航");
                $('.nav-btn').children('.iconfont').removeClass('icon-search').addClass('icon-other');
                $('.ip-group').show();
                $('.qrcodes').show();
                $('.link-nav').removeClass('link-nav-fixed');
                $('.container').removeClass('container-fixed');
            }
        }

總結

主要是scroll, scrollTop(), click, show(), hide方法和position: fixed等屬性的理解和使用。需要注意的是，一開始就調用fixedNav()，是用於當頁面刷新且未滾動，但頁面已不在頂部的位置時（也就是刷新頁面后看不到頂部導航的位置），出現吸頂的導航的效果。