1. 语法 this.$nextTick(回调函数)
2. 作用 在下一次DOM 更新结束后执行其指定的回调
3. 什么时间用 当改变数据后，要基于更新后新的DOM进行某些操作时，要在nextTick 所指定的回调函数中执行。
1. App.vue
<template>
<div id="root">
<div class="todo-container">
<div class="todo-wrap">
<!-- @addTodo 事件名 addTodo 回调名-->
<MyHeader @addTodo="addTodo"/>
<!--父亲给儿子传数据 父亲通过数据绑定传数据 儿子通过 props:['todos'],//声明接收todo 对象 -->
<MyList :todos="todos" :checkTodo="checkTodo" :deleteTodo="deleteTodo"/>
<MyFooter :todos="todos" @checkAllTodo="checkAllTodo" @clearAllTodo="clearAllTodo"/>
</div>
</div>
</div>
</template>
<script>
//样式的引入和这里有关系
import pubsub from 'pubsub-js'
import MyHeader from './components/MyHeader.vue';
import MyList from './components/MyList.vue';
import MyFooter from './components/MyFooter.vue';
export default {
name: 'App',
components: {
MyHeader,
MyList,
MyFooter
},
data(){
return {
todos:JSON.parse(localStorage.getItem("todos"))||[]
}
},
methods:{
// 添加一个todo
addTodo(todoObj){
// console.log('我是app组件,我收到了数据x==',todoObj);
this.todos.unshift(todoObj)
},
//勾选or 取消勾选 todo
checkTodo(id){
this.todos.forEach((todo)=>{
if(todo.id===id) todo.done=!todo.done
})
},
//删除一个todo
deleteTodo(_,id){
this.todos=this.todos.filter((todo)=>{
return todo.id!==id;
})
},
//更新一个todo
updateTodo(id,title){
this.todos.forEach((todo)=>{
if(todo.id===id) todo.title=title;
})
},
//全选or全不选
checkAllTodo(done){
this.todos.forEach((todo)=>{
todo.done=done
})
},
clearAllTodo(){
this.todos=this.todos.filter((todo)=>{
return !todo.done
})
}
},
watch:{
// todos(value){
// localStorage.setItem("todos", JSON.stringify(value));
// }
todos:{
deep:true,
handler(value){
localStorage.setItem("todos", JSON.stringify(value));
}
}
},
mounted(){
this.$bus.$on('checkTodo',this.checkTodo)
//this.$bus.$on('deleteTodo',this.deleteTodo)
this.pubId=pubsub.subscribe('deleteTodo',this.deleteTodo)
this.$bus.$on('updateTodo',this.updateTodo)
},
beforeDestroy(){
this.$bus.$off('checkTodo')
//this.$bus.$off('deleteTodo')
pubsub.unsubscribe(this.pubId)
this.$bus.$off('updateTodo')
}
}
</script>
<style>
/* 整体样式 */
body {
background: rgba(230, 241, 245, 0.816);
}
.btn {
display: inline-block;
padding: 4px 12px;
margin-bottom: 0;
font-size: 14px;
line-height: 20px;
text-align: center;
vertical-align: middle;
cursor: pointer;
box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2),
0 1px 2px rgba(0, 0, 0, 0.05);
border-radius: 4px;
}
.btn-danger {
color: #fff;
background-color: #da4f49;
border: 1px solid #bd362f;
margin-left:5px;
}
.btn-edit {
color: #fff;
background-color: skyblue;
border: 1px solid skyblue;
}
.btn-danger:hover {
color: #fff;
background-color: #bd362f;
}
.btn:focus {
outline: none;
}
.todo-container {
width: 600px;
margin: 0 auto;
}
.todo-container .todo-wrap {
padding: 10px;
border: 1px solid #ddd;
border-radius: 5px;
}
</style>
2. MyItem.vue
<template>
<li>
<label>
<input type="checkbox" :checked="todo.done" @click="handlerCheck(todo.id)"/>
<span v-show="!todo.isEdit">{{todo.title}}</span>
<input v-show="todo.isEdit" type="text" :value="todo.title"
@blur="handlerBlur(todo,$event)"
ref="inputTitle"/>
</label>
<button class="btn btn-danger" @click="hadnlerDelete(todo.id)">删除</button>
<button v-show="!todo.isEdit" class="btn btn-edit" @click="handlerEdit(todo)">编辑</button>
</li>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:"MyItem",
props:['todo'],//声明接收todo 对象
mounted(){
//console.log(this.todo);
},
methods:{
//勾选或者取消勾选
handlerCheck(id){
//通知app 组件 将对应的todo 对象的done 值取反
//console.log("id",id);
//this.checkTodo(id);
this.$bus.$emit('checkTodo',id)
},
//闪促
hadnlerDelete(id){
if(confirm('确定删除么')){
//console.log("id",id);
//通知app 删除一个对象
//this.deleteTodo(id);
// this.$bus.$emit('deleteTodo',id)
pubsub.publish('deleteTodo',id)
}
},
handlerEdit(todo){
if(todo.hasOwnProperty('isEdit')){
todo.isEdit=true;
}else{
this.$set(todo,'isEdit',true)
}
this.$nextTick(function(){
this.$refs.inputTitle.focus()
})
},
//失去焦点回调 真正执行修改逻辑
handlerBlur(todo,e){
todo.isEdit=false;
if(!e.target.value.trim()) return alert('不能为空')
this.$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:hover {
background-color: grey;
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:hover button {
display: block;
}
li:before {
content: initial;
}
li:last-child {
border-bottom: none;
}
</style>