这篇文章将为大家详细讲解有关微信小程序中怎么实现一个下拉菜单效果，文章内容质量较高，因此小编分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。
//wcss
.menu {
display: block;
height: 28px;
position: relative;
}
.menu dt {
font-size: 15px;
float: left;
width: 33%;
height: 38px;
border-right: 1px solid #d2d2d2;
border-bottom: 1px solid #d2d2d2;
text-align: center;
background-color: #f4f4f4;
color: #5a5a5a;
line-height: 38px;
z-index: 2;
}
.menu dd {
position: absolute;
width: 100%;
margin-top: 40px;
left: 0;
z-index: -99;
}
.menu li {
font-size: 14px;
line-height: 34px;
color: #575757;
height: 34px;
display: block;
padding-left: 8px;
background-color: #fff;
border-bottom: 1px solid #dbdbdb;
}
.menu li.highlight {
background-color: #f4f4f4;
color: #48c23d;
}
.show {
visibility: visible;
}
.hidden {
visibility: hidden;
}
//wxml
<dl class="menu">
<block wx:for="{{reportData}}" wx:key="idMenu" wx:for-item="menuItem" wx:for-index="idMenu">
<dt data-index="{{idMenu}}" bindtap="tapMainMenu">{{menuItem.reportType}}</dt>
<dd class="{{subMenuDisplay[idMenu]}}" animation="{{animationData[idMenu]}}">
<ul wx:for="{{menuItem.chilItem}}" wx:key="chilItem.ID" wx:for-item="chilItem" wx:for-index="idChil">
<li class="{{subMenuHighLight[idMenu][idChil]}}" bindtap="tapSubMenu" data-index="{{idMenu}}-{{idChil}}">{{chilItem.Name}}</li>
</ul>
<picker class="timePicker" mode="date" value="{{dateValue}}" bindchange="datePickerBindchange" start="1999-01-01" end="2999-12-12"> 时间：{{dateValue}}</picker>
</dd>
</block>
</dl>
//js
//数据源
var ReportDataSync = [
{
reportType: "日报1",
chilItem: [
{ ID: 1, Name: "日报1", ReportUrl: "DailyReport.aspx", Type: 1 },
{ ID: 2, Name: "日报2", ReportUrl: "DailyReport.aspx", Type: 1 },
{ ID: 3, Name: "日报3", ReportUrl: "DailyReport.aspx", Type: 1 }]
},
{
reportType: "目录2",
chilItem: [
{ ID: 1, Name: "目录1", ReportUrl: "DailyReport.aspx", Type: 2 },
{ ID: 2, Name: "目录2", ReportUrl: "DailyReport.aspx", Type: 2 },
{ ID: 3, Name: "目录3", ReportUrl: "DailyReport.aspx", Type: 2 },
{ ID: 4, Name: "目录4", ReportUrl: "DailyReport.aspx", Type: 2 }]
},
{
reportType: "月报3",
chilItem: [
{ ID: 1, Name: "月报1", ReportUrl: "DailyReport.aspx", Type: 1 },
{ ID: 2, Name: "月报2", ReportUrl: "DailyReport.aspx", Type: 2 }]
}
]
//定义字段
var initSubMenuDisplay = []
var initSubMenuHighLight = []
var initAnimationData = []
/// 初始化DropDownMenu
loadDropDownMenu()
that.setData({
reportData: ReportDataSync,//菜单数据
subMenuDisplay: initSubMenuDisplay, //一级
subMenuHighLight: initSubMenuHighLight, //二级
animationData: initAnimationData //动画
})
//一级菜单点击
tapMainMenu: function (e) {
//获取当前一级菜单标识
var index = parseInt(e.currentTarget.dataset.index);
//改变显示状态
for (var i = 0; i < initSubMenuDisplay.length; i++) {
if (i == index) {
if (this.data.subMenuDisplay[index] == "show") {
initSubMenuDisplay[index] = 'hidden'
} else {
initSubMenuDisplay[index] = 'show'
}
} else {
initSubMenuDisplay[i] = 'hidden'
}
}
this.setData({
subMenuDisplay: initSubMenuDisplay
})
this.animation(index)
},
//二级菜单点击
tapSubMenu: function (e) {
//隐藏所有一级菜单
//this.setData({
//subMenuDisplay: initSubMenuDisplay()
//});
// 当前二级菜单的标识
var indexArray = e.currentTarget.dataset.index.split('-');
// 删除所在二级菜单样式
for (var i = 0; i < initSubMenuHighLight.length; i++) {
if (indexArray[0] == i) {
for (var j = 0; j < initSubMenuHighLight[i].length; j++) {
initSubMenuHighLight[i][j] = '';
}
}
}
//给当前二级菜单添加样式
initSubMenuHighLight[indexArray[0]][indexArray[1]] = 'highlight';
//刷新样式
this.setData({
subMenuHighLight: initSubMenuHighLight
});
// 设置动画
this.animation(indexArray[0]);
},
//菜单动画
animation: function (index) {
// 定义一个动画
var animation = wx.createAnimation({
duration: 400,
timingFunction: 'linear',
})
// 是显示还是隐藏
var flag = this.data.subMenuDisplay[index] == 'show' ? 1 : -1;
// 使之Y轴平移
animation.translateY(flag * ((initSubMenuHighLight[index].length + 1) * 38)).step();
// 导出到数据，绑定给view属性
var animationStr = animation.export();
// 原来的数据
var animationData = this.data.animationData;
animationData[index] = animationStr;
this.setData({
animationData: animationData
});
}
/// <summary>
/// 初始化DropDownMenu
/// 1.一级目录 initSubMenuDisplay ：['hidden']
/// 2.二级目录 initSubMenuHighLight ：[['',''],['','','','']]]
/// </summary>
function loadDropDownMenu() {
for (var i = 0; i < ReportDataSync.length; i++) {
//一级目录
initSubMenuDisplay.push('hidden')
//二级目录
var report = []
for (var j = 0; j < ReportDataSync[i].chilItem.length; j++) {
report.push([''])
}
initSubMenuHighLight.push(report)
//动画
initAnimationData.push("")
}
}关于微信小程序中怎么实现一个下拉菜单效果就分享到这里了，希望以上内容可以对大家有一定的帮助，可以学到更多知识。如果觉得文章不错，可以把它分享出去让更多的人看到。
