$nextTick
这是一个生命周期钩子
this.$nextTick(回调函数)
在下一次DOM更新结束后执行其指定的回调
什么时候用:当数据改变后,要基于更新后的新DOM进行某些操作时,要在nextTick所指定的回调函数中执行。
使用$nextTick优化Todo-List
src/components/MyItem.vue
<template>
<li>
<label>
<input type="checkbox" :checked="todo.done" @change="handleCheck(todo.id)"/>
<!-- 如下代码也能实现功能,但是不太推荐,因为有点违反原则,因为修改了props -->
<!-- <input type="checkbox" v-model="todo.done"/> -->
<span v-show="!todo.isEdit">{{todo.title}}</span>
<input
type="text"
v-show="todo.isEdit"
:value="todo.title"
@blur="handleBlur(todo,$event)"
ref="inputTitle"
>
</label>
<button class="btn btn-danger" @click="handleDelete(todo.id)">删除</button>
<button v-show="!todo.isEdit" class="btn btn-edit" @click="handleEdit(todo)">编辑</button>
</li>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:'MyItem',
//声明接收todo
props:['todo'],
methods: {
//勾选or取消勾选
handleCheck(id){
//通知App组件将对应的todo对象的done值取反
// this.checkTodo(id)
this.$bus.$emit('checkTodo',id)
},
//删除
handleDelete(id){
if(confirm('确定删除吗?')){
//通知App组件将对应的todo对象删除
// this.deleteTodo(id)
// this.$bus.$emit('deleteTodo',id)
pubsub.publish('deleteTodo',id)
}
},
//编辑
handleEdit(todo){
if(todo.hasOwnProperty('isEdit')){
todo.isEdit = true
}else{
// console.log('@')
this.$set(todo,'isEdit',true)
}
this.$nextTick(function(){
this.$refs.inputTitle.focus()
})
},
//失去焦点回调(真正执行修改逻辑)
handleBlur(todo,e){
todo.isEdit = false
if(!e.target.value.trim()) return alert('输入不能为空!')
this.$bus.$emit('updateTodo',todo.id,e.target.value)
}
},
}
</script>
<style scoped>
/*item*/
li {
list-style: none;
height: 36px;
line-height: 36px;
padding: 0 5px;
border-bottom: 1px solid #ddd;
}
li label {
float: left;
cursor: pointer;
}
li label li input {
vertical-align: middle;
margin-right: 6px;
position: relative;
top: -1px;
}
li button {
float: right;
display: none;
margin-top: 3px;
}
li:before {
content: initial;
}
li:last-child {
border-bottom: none;
}
li:hover{
background-color: #ddd;
}
li:hover button{
display: block;
}
</style>
过度与动画
Vue封装的过度与动画:在插入、更新或移除DOM元素时,在合适时候给元素添加样式类名
写法:
- 准备好样式
元素进入的样式
i. v-enter
ii.v-enter-active
iii.v-enter-to
元素离开的样式
i.v-leave
ii.v-leave-active
iii.v-leave-to - 使用 包裹要过度的元素,并配置name属性,此时需要将上面的样式名的v换为name
- 要让页面一开始就要显示动画,需要添加appear
<template>
<div>
<button @click="isShow = !isShow">显示/隐藏</button>
<transition name="hello" appear>
<h1 v-show="isShow">你好啊!</h1>
</transition>
</div>
</template>
<script>
export default {
name:'Test',
data() {
return {
isShow:true
}
},
}
</script>
<style scoped>
h1{
background-color: orange;
}
.hello-enter-active{
animation: atguigu 0.5s linear;
}
.hello-leave-active{
animation: atguigu 0.5s linear reverse;
}
@keyframes atguigu {
from{
transform: translateX(-100%);
}
to{
transform: translateX(0px);
}
}
</style>
- 备注:若有多个元素需过度,则需要使用,且每个元素都要指定key值
<transition name="hello" appear>
<h1 v-show="isShow">你好啊!</h1>
</transition>
- 第三方动画库 animate.css
<template>
<div>
<button @click="isShow = !isShow">显示/隐藏</button>
<transition-group
appear
name="animate__animated animate__bounce"
enter-active-class="animate__swing"
leave-active-class="animate__backOutUp"
>
<h1 v-show="!isShow" key="1">你好啊!</h1>
<h1 v-show="isShow" key="2">尚硅谷!</h1>
</transition-group>
</div>
</template>
src/App.vue
<template>
<div>
<Test/>
<Test2/>
<Test3/>
</div>
</template>
<script>
import Test from './components/Test'
import Test2 from './components/Test2'
import Test3 from './components/Test3'
export default {
name:'App',
components:{Test,Test2,Test3},
}
</script>
src/components/test.vue
<template>
<div>
<button @click="isShow = !isShow">显示/隐藏</button>
<transition name="hello" appear>
<h1 v-show="isShow">你好啊!</h1>
</transition>
</div>
</template>
<script>
export default {
name:'Test',
data() {
return {
isShow:true
}
},
}
</script>
<style scoped>
h1{
background-color: orange;
}
.hello-enter-active{
animation: atguigu 0.5s linear;
}
.hello-leave-active{
animation: atguigu 0.5s linear reverse;
}
@keyframes atguigu {
from{
transform: translateX(-100%);
}
to{
transform: translateX(0px);
}
}
</style>
src/components/test2.vue
<template>
<div>
<button @click="isShow = !isShow">显示/隐藏</button>
<transition-group name="hello" appear>
<h1 v-show="!isShow" key="1">你好啊!</h1>
<h1 v-show="isShow" key="2">尚硅谷!</h1>
</transition-group>
</div>
</template>
<script>
export default {
name:'Test',
data() {
return {
isShow:true
}
},
}
</script>
<style scoped>
h1{
background-color: orange;
}
/* 进入的起点、离开的终点 */
.hello-enter,.hello-leave-to{
transform: translateX(-100%);
}
.hello-enter-active,.hello-leave-active{
transition: 0.5s linear;
}
/* 进入的终点、离开的起点 */
.hello-enter-to,.hello-leave{
transform: translateX(0);
}
</style>
src/components/test3.vue
<template>
<div>
<button @click="isShow = !isShow">显示/隐藏</button>
<transition-group
appear
name="animate__animated animate__bounce"
enter-active-class="animate__swing"
leave-active-class="animate__backOutUp"
>
<h1 v-show="!isShow" key="1">你好啊!</h1>
<h1 v-show="isShow" key="2">尚硅谷!</h1>
</transition-group>
</div>
</template>
<script>
import 'animate.css'
export default {
name:'Test',
data() {
return {
isShow:true
}
},
}
</script>
<style scoped>
h1{
background-color: orange;
}
</style>
使用动画优化Todo-List
src/components/MyList.vue
<template>
<ul class="todo-main">
<transition-group name="todo" appear>
<MyItem
v-for="todoObj in todos"
:key="todoObj.id"
:todo="todoObj"
/>
</transition-group>
</ul>
</template>
<script>
import MyItem from './MyItem'
export default {
name:'MyList',
components:{MyItem},
//声明接收App传递过来的数据
props:['todos']
}
</script>
<style scoped>
/*main*/
.todo-main {
margin-left: 0px;
border: 1px solid #ddd;
border-radius: 2px;
padding: 0px;
}
.todo-empty {
height: 40px;
line-height: 40px;
border: 1px solid #ddd;
border-radius: 2px;
padding-left: 5px;
margin-top: 10px;
}
.todo-enter-active{
animation: atguigu 0.5s linear;
}
.todo-leave-active{
animation: atguigu 0.5s linear reverse;
}
@keyframes atguigu {
from{
transform: translateX(100%);
}
to{
transform: translateX(0px);
}
}
</style>
安装animate.css动画
1.npm install animate.css
引用
import ‘animate.css’