Vue 实现展开折叠效果
限定条数的情况下，超出部分不做展示，会变成更多条件按钮，让其用户自行选择，如果需要，可以点击更多按钮，再进行展示
一、目标实现效果
除了使用jQuery的方式实现上述效果，同样可以在Vue实现，下面是解决办法：
二、步骤
1.创建collapse.js文件
const elTransition =
"0.3s height ease-in-out, 0.3s padding-top ease-in-out, 0.3s padding-bottom ease-in-out";
const Transition = {
"before-enter"(el) {
el.style.transition = elTransition;
if (!el.dataset) el.dataset = {};
el.dataset.oldPaddingTop = el.style.paddingTop;
el.dataset.oldPaddingBottom = el.style.paddingBottom;
el.style.height = 0;
el.style.paddingTop = 0;
el.style.paddingBottom = 0;
},
enter(el) {
el.dataset.oldOverflow = el.style.overflow;
if (el.scrollHeight !== 0) {
el.style.height = el.scrollHeight + "px";
el.style.paddingTop = el.dataset.oldPaddingTop;
el.style.paddingBottom = el.dataset.oldPaddingBottom;
} else {
el.style.height = "";
el.style.paddingTop = el.dataset.oldPaddingTop;
el.style.paddingBottom = el.dataset.oldPaddingBottom;
}
el.style.overflow = "hidden";
},
"after-enter"(el) {
el.style.transition = "";
el.style.height = "";
el.style.overflow = el.dataset.oldOverflow;
},
"before-leave"(el) {
if (!el.dataset) el.dataset = {};
el.dataset.oldPaddingTop = el.style.paddingTop;
el.dataset.oldPaddingBottom = el.style.paddingBottom;
el.dataset.oldOverflow = el.style.overflow;
el.style.height = el.scrollHeight + "px";
el.style.overflow = "hidden";
},
leave(el) {
if (el.scrollHeight !== 0) {
el.style.transition = elTransition;
el.style.height = 0;
el.style.paddingTop = 0;
el.style.paddingBottom = 0;
}
},
"after-leave"(el) {
el.style.transition = "";
el.style.height = "";
el.style.overflow = el.dataset.oldOverflow;
el.style.paddingTop = el.dataset.oldPaddingTop;
el.style.paddingBottom = el.dataset.oldPaddingBottom;
}
};
export default {
name: "collapseTransition",
functional: true,
render(h, { children }) {
const data = {
on: Transition
};
return h("transition", data, children);
}
};
2.再次封装组件，提供slot插槽
<template>
<view>
<collapse>
<div class="collapse-wrap" v-show="isActive">
<!-- @slot default -->
<slot></slot>
</div>
</collapse>
</view>
</template>
<script>
/**
* @description 折叠收缩组件
* @created by lishengsong
* @date 2020-04-24
*/
import collapse from '@/plugins/uiTools/collapse.js'
export default {
components: {
collapse
},
props: {
isActive: {
type: Boolean,
default: true
}
},
onLoad() {
console.log(collapse);
},
watch: {
isActive(val) {
return val
}
}
}
</script>
<style>
</style>
递归组件-树形控件预览及问题
在编写树形组件时遇到的问题：
- 组件如何才能递归调用？
- 递归组件点击事件如何传递？
一、树形控件基本结构及样式
<template>
<ul class="vue-tree">
<li class="tree-item">
<div class="tree-content"><!--节点内容-->
<div class="expand-arrow"></div><!--展开或收缩节点按钮-->
<div class="tree-label">小学</div><!--节点文本内容-->
</div>
<ul class="sub-tree"><!--子节点-->
<li class="tree-item expand">
<div class="tree-content">
<div class="expand-arrow"></div>
<div class="tree-label">语文</div>
</div>
</li>
<li class="tree-item">
<div class="tree-content">
<div class="expand-arrow"></div>
<div class="tree-label">数学</div>
</div>
</li>
</ul>
</li>
</ul>
</template>
<style lang="stylus">
.vue-tree{
list-style: none;
padding: 0;
margin: 0;
.tree-item{
cursor: pointer;
transition: background-color .2s;
.tree-content{
position: relative;
padding-left: 28px;
&:hover{
background-color: #f0f7ff;
}
}
.expand-arrow{
position: absolute;
top: 0;
left: 0;
width: 28px;
height: 28px;
cursor: pointer;
&::after{
position: absolute;
top: 50%;
left: 50%;
display: block;
content: ' ';
border-width: 5px;
border-style: solid;
border-color: transparent;
border-left-color: #ccc;
margin: -5px 0 0 -2.5px;
transition: all .2s;
}
}
&.expand{
&>.tree-content{
background-color: #f0f7ff;
&>.expand-arrow{
&::after{
transform: rotate(90deg);
margin: -2.5px 0 0 -5px;
}
}
}
}
.tree-label{
height: 28px;
line-height: 28px;
font-size: 14px;
}
.sub-tree{
display: none;
list-style: none;
padding: 0 0 0 28px;
margin: 0;
}
&.expand>.sub-tree{
display: block;
}
&.no-child{
&>.tree-content{
&>.expand-arrow{
display: none;
}
}
}
}
}
</style>
二、组件目录及数据结构
目录结构
vue-tree
-
VueTree.vue 树形控件父组件
-
TreeItem.vue 树形控件递归组件
树形控件数据结构
let treeData = [
{
text: "一级", // 显示的文字
expand: false, // 默认是否展开
children: [ // 子节点
{
text: "一级-1",
expand: false,
},
{
text: "一级-2",
expand: false,
children: [
{
text: "一级-2-1",
expand: false,
},
{
text: "一级-2-2",
expand: false,
}
]
}
]
}
];
1.TreeItem.vue 代码
<template>
<li class="tree-item" :class="{expand: isExpand, 'no-child': !treeItemData.children || treeItemData.children.length === 0}">
<div class="tree-content" @click="_clickEvent">
<div class="expand-arrow" @click.stop="expandTree()"></div>
<div class="tree-label">{{treeItemData.text}}</div>
</div>
<ul class="sub-tree" v-if="treeItemData.children && treeItemData.children.length > 0">
<!--TreeItem组件中调用TreeItem组件-->
<TreeItem
v-for="item in treeItemData.children"
:tree-item-data="item"
:key="uuid()"
:tree-click-event="treeClickEvent"></TreeItem>
</ul>
</li>
</template>
<script>
export default {
name: "TreeItem",
props: {
treeItemData: {
type: Object,
default(){
return {};
}
},
// 节点点击事件
treeClickEvent: {
type: Function,
default() {
return function () {};
}
}
},
data(){
return {
// 节点是否展开
isExpand: this.treeItemData.expand || false
}
},
methods: {
// 展开/收缩
expandTree(flag){
if(!this.treeItemData.children || this.treeItemData.children.length === 0){
return;
}
if(typeof flag === 'undefined'){
flag = !this.isExpand;
}else{
flag = !!flag;
}
this.isExpand = flag;
},
// 创建一个唯一id
uuid(){
let str = Math.random().toString(32);
str = str.substr(2);
return str;
},
// 节点点击事件
_clickEvent(){
// 如果有传递事件函数，则调用事件函数并传递当前节点数据及组件
if(this.treeClickEvent && typeof this.treeClickEvent === 'function'){
this.treeClickEvent(this.treeItemData, this);
}
}
}
}
</script>
（一）解决组件如何才能递归调用问题
在组件模板内调用自身必须明确定义组件的name属性，并且递归调用时组件名称就是name属性。如在TreeItem.vue组件中组件的name名称为'TreeItem'，那么在template中调用时组件名称就必须是。
当然也可以全局注册组件，具体可以查看vue官方文档 递归组件
（二）解决递归组件点击事件如何传递问题
我这里的解决方案是使用props将事件函数传递进来，在点击节点的时候调用事件函数，并把相应的数据传递进去。
之前也尝试过使用$emit的形式并把数据传递过去，由于是递归组件，这样一直$emit，到最外层时传递的数据就变了，比如传递是第3层节点的数据，到最后执行时数据就变成第1层节点的数据了
2.VueTree.vue 组件
<template>
<ul class="vue-tree">
<TreeItem
v-for="(item, index) in treeData"
:key="index"
:treeItemData="item"
:tree-click-event="treeClickEvent"></TreeItem>
</ul>
</template>
<script>
import TreeItem from "./TreeItem";
export default {
name: "VueTreeMenu",
components: {
TreeItem
},
props: {
// 树形控件数据
treeData: {
type: Array,
default(){
return [];
}
},
// 节点点击事件
treeClickEvent: {
type: Function,
default() {
return function () {};
}
}
}
}
</script>
<style lang="stylus">
.vue-tree{
list-style: none;
padding: 0;
margin: 0;
.tree-item{
cursor: pointer;
transition: background-color .2s;
.tree-content{
position: relative;
padding-left: 28px;
&:hover{
background-color: #f0f7ff;
}
}
.expand-arrow{
position: absolute;
top: 0;
left: 0;
width: 28px;
height: 28px;
cursor: pointer;
&::after{
position: absolute;
top: 50%;
left: 50%;
display: block;
content: ' ';
border-width: 5px;
border-style: solid;
border-color: transparent;
border-left-color: #ccc;
margin: -5px 0 0 -2.5px;
transition: all .2s;
}
}
&.expand{
&>.tree-content{
background-color: #f0f7ff;
&>.expand-arrow{
&::after{
transform: rotate(90deg);
margin: -2.5px 0 0 -5px;
}
}
}
}
.tree-label{
height: 28px;
line-height: 28px;
font-size: 14px;
}
.sub-tree{
display: none;
list-style: none;
padding: 0 0 0 28px;
margin: 0;
}
&.expand>.sub-tree{
display: block;
}
&.no-child{
&>.tree-content{
/*padding-left: 0;*/
&>.expand-arrow{
display: none;
}
}
}
}
}
</style>
3.使用树形组件
<template>
<div class="app" id="app">
<VueTree :tree-data="treeData2" :tree-click-event="treeClickEvent"></VueTree>
</div>
</template>
<script>
import VueTree from "./components/vue-tree/VueTree";
export default {
name: 'app',
data(){
return {
treeData2: [
{
text: "一级", // 显示的文字
expand: false, // 默认是否展开
children: [
{
text: "二级-1",
expand: false,
},
{
text: "二级-2",
expand: false,
children: [
{
text: "三级-1",
expand: false,
},
{
text: "三级-2",
expand: false,
children: [
{
text: "四级-1",
expand: false,
}
]
}
]
}
]
},
{
text: "一级-2",
expand: false
}
]
}
},
methods: {
treeClickEvent(item, treeItem){
console.log(item);
}
},
components: {
VueTree
}
}
</script>
