Vue render函数实战之实现tabs选项卡组件

更新时间：2020-08-23 10:06:01 作者：startmvc

用过Elementui库的童鞋肯定知道<el-tabs>组件，简单、好用、可以自定义标签页，不知道广

用过Element ui库的童鞋肯定知道<el-tabs>组件，简单、好用、可以自定义标签页，不知道广大童鞋们在刚开始使用<el-tabs>组件的时候有没有想过它是如何实现的？我咋刚开始使用<el-tabs>组件的时候就有去想过，也想去实现一个超级简单的tabs选项卡组件，无奈当时功力不够，未能实现。最近的一个简单项目中正好要用到选项卡组件，由于项目简单也就没有使用任何第三方库，于是就自己动手写了个选项卡组件。

1、实现tabs选项卡组件的思考


<el-tabs v-model="activeName" @tab-click="handleClick">
 <el-tab-pane label="用户管理" name="first">用户管理</el-tab-pane>
 <el-tab-pane label="配置管理" name="second">配置管理</el-tab-pane>
 <el-tab-pane label="角色管理" name="third">角色管理</el-tab-pane>
 <el-tab-pane label="定时任务补偿" name="fourth">定时任务补偿</el-tab-pane>
</el-tabs>

问题：

如何根据<el-tab-pane>来生成标签页？
如何过滤<el-tabs>组件中的子元素，使得在使用的时候只显示<el-tab-pane>，而不会显示其他组件或div之类的元素？

2、实现思路

想根据<el-tab-pane>来生成标签页就需要使用到<slot>，使用<slot>用<template>的形式肯定是不行的，因为无法获取到<slot>的数量；使用<template>的形式行不通，那就只有使用render函数了过滤<el-tabs>组件中的子元素也需要使用render函数

3、代码实现

index.js


import PTabs from './PTabs';
import PTabPane from './PTabPane';

export default function tabsInstall(Vue) {
 if(tabsInstall.installed){
 return;
 }
 Vue.component('PTabs', PTabs);
 Vue.component('PTabPane', PTabPane);
}

PTabs.vue


<script>
 import PTabNav from './PTabNav';
 export default {
 name: "PTabs",
 props: {
 value: {
 type: [String, Number],
 default: ''
 },
 beforeClick: {
 type: Function,
 default(){
 return function () {};
 }
 }
 },
 components: {
 PTabNav
 },
 data(){
 return {
 pTabPanes: [],
 currentName: this.value || 0
 }
 },
 methods: {
 addPane(pane){
 this.pTabPanes.push(pane);
 if(!this.currentName){
 this.setCurrentName(this.pTabPanes[0].name);
 }
 },
 removePane(pane){
 let index = this.pTabPanes.indexOf(pane);
 if(index > -1){
 this.pTabPanes.splice(index, 1);
 }
 },
 setCurrentName(name){
 if(this.currentName !== name){
 this.currentName = name;
 this.$emit('input', name);
 }
 },
 // 标签页点击事件
 handTabNavClick(name, pane, e){
 if(this.currentName === name || pane.disabled){
 return;
 }
 let before = this.beforeClick();
 if(before && before.then){
 before.then(() => {
 this.setCurrentName(name);
 this.$emit('tabClick', pane, e);
 })
 }else{
 this.setCurrentName(name);
 this.$emit('tabClick', pane, e);
 }
 }
 },
 watch: {
 value(newVal){
 this.setCurrentName(newVal);
 },
 currentName(){
 this.$nextTick(() => {
 this.$refs.p_tab_nav.scrollToActiveTab();
 });
 }
 },
 render(h) {
 let {$scopedSlots} = this;
 let $default = $scopedSlots.default();
 let qTabPanes = $default.map(item => {
 /* 过滤<PTabs>xxx</PTabs>中传递的xxx内容。这里只接收<PTabPane>组件，因为我们需要根据<PTabPane>组件的数量来生成
 * <PTabNav>组件，如果参差了其它节点则会导致不能正确生成<PTabNav>组件 */
 if(item.componentOptions && item.componentOptions.tag === 'PTabPane'){
 return item;
 }
 });
 let qTab = h('PTabNav', {
 props: {
 // 将tab-pane传递给 <PTabNav>组件，<PTabNav>组件就知道要有多少个tab-item了
 tabPanes: this.pTabPanes,
 handTabNavClick: this.handTabNavClick
 },
 ref: 'p_tab_nav'
 });
 let qTabBody = h('div', {
 staticClass: 'p-tabs_content'
 }, qTabPanes);

 console.log($default)
 return h('div', {
 staticClass: 'p-tabs'
 }, [qTab, qTabBody]);
 },
 mounted() {
 //console.log(this)
 this.$nextTick(() => {
 this.$refs.p_tab_nav.scrollToActiveTab();
 });
 }
 }
</script>
<style lang="stylus">
.p-tabs{
 .p-tabs_header{
 position: relative;
 margin-bottom: 15px;
 &.is-scrollable{
 padding-left: 20px;
 padding-right: 20px;
 }
 }
 .p-tabs_nav-prev,
 .p-tabs_nav-next{
 position: absolute;
 top: 0;
 width: 20px;
 height: 100%;
 display: none;
 &::before{
 position: absolute;
 content: ' ';
 font-size: 0;
 line-height: 0;
 width: 10px;
 height: 10px;
 top: 50%;
 left: 50%;
 border-top: 1px solid #eee;
 border-left: 1px solid #eee;
 margin: -5px 0 0 -5px;
 }
 cursor: pointer;
 &.disabled{
 cursor: default;
 border-color: #aaa;
 }
 }
 .p-tabs_nav-prev{
 left: 0;
 &:before{
 transform: rotate(-45deg);
 }
 }
 .p-tabs_nav-next{
 right: 0;
 &:before{
 transform: rotate(135deg);
 }
 }
 .p-tabs_header{
 &.is-scrollable{
 .p-tabs_nav-prev,
 .p-tabs_nav-next{
 display: block;
 }
 }
 }
 .p-tabs_nav-scroll{
 overflow: hidden;
 }
 .p-tabs_nav-list{
 position: relative;
 float: left;
 white-space: nowrap;
 transition: transform .3s;
 }
 .p-tabs_nav-item{
 display: inline-block;
 height: 40px;
 line-height: 40px;
 padding: 0 20px;
 color: #fff;
 cursor: pointer;
 &.active,
 &:hover{
 color: #ffb845;
 }
 &.disabled{
 cursor: not-allowed;
 color: #aaa;
 &:hover{
 color: #aaa;
 }
 }
 }
 .p-tabs_content{
 position: relative;
 overflow: hidden;
 }
 .p-tabs-pane{
 color: #fff;
 }
}
</style>

PTabPane.vue


<template>
 <div class="p-tabs-pane" v-show="show">
 <slot></slot>
 </div>
</template>
<script>
 export default {
 name: "PTabPane",
 props: {
 label: {
 type: String,
 default: ''
 },
 name: {
 type: [String, Number],
 default: ''
 },
 disabled: {
 type: Boolean,
 default: false
 }
 },
 data(){
 return {
 loaded: false
 }
 },
 computed: {
 show(){
 if(this.$parent.currentName === this.name){
 if(!this.loaded){
 this.loaded = true;
 }
 return true;
 }
 return false;
 }
 },
 watch: {
 label(){
 // label更新的时候强制更新父组件，以触发PTabNav才能更新
 this.$parent.$forceUpdate();
 }
 },
 mounted() {
 // 当当前组件创建的时候将当前组件添加到父组件的pTabPanes中，以触发PTabNav才能更新
 this.$parent.addPane(this);
 },
 destroyed() {
 if(this.$el && this.$el.parentNode){
 this.$el.parentNode.removeChild(this.$el);
 }
 // 当当前组件销毁时需从父组件中的pTabPanes中移除当前组件，以触发PTabNav才能更新
 this.$parent.removePane(this);
 }
 }
</script>

PTabNav.vue


<script>
 function noop() {};

 export default {
 name: "PTabNav",
 props: {
 tabPanes: {
 type: Array,
 default(){
 return [];
 }
 },
 handTabNavClick: {
 type: Function,
 default(){
 return function () {};
 }
 }
 },
 data(){
 return {
 navPrevDisabled: true,
 navNextDisabled: true,
 // 控制左右箭头显示
 scrollable: false,
 listOffset: 0
 }
 },
 methods: {
 navPrevClickEvent(){
 if(!this.navPrevDisabled){
 let navScrollW = this.$refs.nav_scroll.offsetWidth;
 let navListW = this.$refs.nav_list.offsetWidth;
 let maxTransformX = 0;
 let transformX = this.listOffset - navScrollW;
 if(transformX < maxTransformX){
 transformX = maxTransformX;
 }
 if(transformX === this.listOffset){
 return;
 }
 console.log('上一页按钮点击了', transformX);
 this.listOffset = transformX;
 if(transformX === 0){
 this.navPrevDisabled = true;
 this.navNextDisabled = false;
 }else if(transformX === (navListW - navScrollW)){
 this.navPrevDisabled = false;
 this.navNextDisabled = true;
 }else{
 this.navPrevDisabled = false;
 this.navNextDisabled = false;
 }
 }
 },
 navNextClickEvent(){
 if(!this.navNextDisabled){
 let navScrollW = this.$refs.nav_scroll.offsetWidth;
 let navListW = this.$refs.nav_list.offsetWidth;
 let maxTransformX = navListW - navScrollW;
 let transformX = this.listOffset + navScrollW;
 if(transformX > maxTransformX){
 transformX = maxTransformX;
 }
 if(transformX === this.listOffset){
 return;
 }
 console.log('下一页按钮点击了', transformX);
 this.listOffset = transformX;
 if(transformX === 0){
 this.navPrevDisabled = true;
 this.navNextDisabled = false;
 }else if(transformX === (navListW - navScrollW)){
 this.navPrevDisabled = false;
 this.navNextDisabled = true;
 }else{
 this.navPrevDisabled = false;
 this.navNextDisabled = false;
 }
 }
 },
 // 计算 .p-tabs_nav-list 是否溢出
 calculateListSpilled(){
 let navScrollW = this.$refs.nav_scroll.offsetWidth;
 let navListW = this.$refs.nav_list.offsetWidth;
 if(navScrollW < navListW){
 this.scrollable = true;
 }else{
 if(this.listOffset > 0){
 this.listOffset = 0;
 }
 this.scrollable = false;
 }
 },
 // 滚动条滚动到激活的tab
 scrollToActiveTab(){
 if(this.scrollable){
 this.$nextTick(() => {
 let navScrollW = this.$refs.nav_scroll.offsetWidth;
 let navList = this.$refs.nav_list;
 let activeTab = navList.querySelector('.active');
 let activeTabOffsetLeft = 0;
 if(activeTab){
 activeTabOffsetLeft = activeTab.offsetLeft;
 }

 let transformX = activeTabOffsetLeft + activeTab.offsetWidth - navScrollW;

 transformX = transformX < 0 ? 0 : transformX;
 this.listOffset = transformX;
 if(transformX === 0){
 this.navPrevDisabled = true;
 this.navNextDisabled = false;
 }else if(transformX === (navList.offsetWidth - navScrollW)){
 this.navPrevDisabled = false;
 this.navNextDisabled = true;
 }else{
 this.navPrevDisabled = false;
 this.navNextDisabled = false;
 }
 });
 }
 }
 },
 computed: {
 listOffsetTran(){
 console.log('dddd',`translateX(-${this.listOffset}px);`)
 return {
 transform: `translateX(-${this.listOffset}px)`
 }
 }
 },
 render(h) {
 /*dom结构
 <div class="p-tabs_header is-scrollable">
 <span class="p-tabs_nav-prev disabled"></span>
 <span class="p-tabs_nav-next"></span>
 <div class="p-tabs_nav-scroll">
 <div class="p-tabs_nav-list">
 <div class="p-tabs_nav-item active">全部</div>
 <div class="p-tabs_nav-item disabled">技术教学</div>
 <div class="p-tabs_nav-item">新手教学</div>
 </div>
 </div>
 </div>
 */
 let navPrev = h('span', {
 staticClass: 'p-tabs_nav-prev',
 'class': {
 disabled: this.navPrevDisabled
 },
 on: {
 click: this.navPrevClickEvent
 }
 });
 let navNext = h('span', {
 staticClass: 'p-tabs_nav-next',
 'class': {
 disabled: this.navNextDisabled
 },
 on: {
 click: this.navNextClickEvent
 }
 });
 // 生成标签页
 let navItems = this.tabPanes.map(item => {
 let $labelSlot = item.$scopedSlots.label ? item.$scopedSlots.label() : null;
 let labelContent = $labelSlot ? $labelSlot : item.label;
 return h('div', {
 staticClass: 'p-tabs_nav-item',
 'class': {
 active: this.$parent.currentName === item.name,
 disabled: item.disabled,
 },
 on: {
 click: (e) => {
 this.handTabNavClick(item.name, item, e);
 }
 }
 }, [labelContent]);
 });
 let navScroll = h('div', {
 staticClass: 'p-tabs_nav-scroll',
 ref: 'nav_scroll'
 }, [
 h('div', {
 staticClass: 'p-tabs_nav-list',
 ref: 'nav_list',
 style: this.listOffsetTran
 }, [navItems])
 ]);

 return h('div', {
 staticClass: 'p-tabs_header',
 'class': {
 'is-scrollable': this.scrollable
 },
 }, [navPrev, navNext, navScroll]);
 },
 updated(){
 this.calculateListSpilled();
 },
 mounted() {
 this.calculateListSpilled();
 }
 }
</script>

4、使用

main.js


// 引入tabs组件
import tabs from './components/p-tabs';
// 全局注册p-tabs组件
Vue.use(tabs);

页面中使用


<PTabs v-model="activeName">
 <PTabPane label="用户管理" name="first">用户管理</PTabPane>
 <PTabPane label="配置管理" name="second">配置管理</PTabPane>
 <PTabPane label="角色管理" name="third">角色管理</PTabPane>
 <PTabPane label="定时任务补偿" name="fourth">定时任务补偿</PTabPane>
</PTabs>

总结

以上所述是小编给大家介绍的Vue render函数实战之实现tabs选项卡组件,希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！如果你觉得本文对你有帮助，欢迎转载，烦请注明出处，谢谢！