写几个小案例来理解vue的组件化编程思想,下面是一个demo.
效果图示:
需求:
header部输入任务,进行添加,在list中显示;
list中每个item项,鼠标移入时,背景变灰并显示delete按钮.点击按钮可删除该项;鼠标移出时,恢复原样;
footer部: 1.根据列表勾选状态及数量显示已完成数和全部数; 2.当已完成数为0时,不显示清除已完成任务按钮; 3.当已完成数等于全部数量时,全选框勾选. 4.当list列表为空时,全选框不勾选; 5.当主动勾选全选时,所有项都勾选,去勾选时所有项去勾选.
项目目录:
代码:
1.全局样式
base.css
/*base*/
body {
background: #fff;
}
.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;
}
.btn-danger:hover {
color: #fff;
background-color: #bd362f;
}
.btn:focus {
outline: none;
}
2.storageUtil.js
/**
* 使用localStorage存储数据的工具模块
* 1.函数
* 2.模块
* 需要向外暴露一个功能还是多个功能
*/
const PROJECTS_KEY = 'project_key'
export default {
saveProjects(val) {
window.localStorage.setItem(PROJECTS_KEY, JSON.stringify(val))
},
readProjects() {
return JSON.parse(window.localStorage.getItem(PROJECTS_KEY) || '[]');
}
}
3.index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>vue_demo</title>
<!-- <link rel="stylesheet" href="./static/css/bootstrap.css">-->
</head>
<body>
<div id="app"></div>
<!-- built files will be auto injected -->
</body>
</html>
4.main.js
import Vue from 'vue'
import App from './App'
import './base.css' // 全局引入base.css文件
new Vue({
el: '#app',
components: { App },
template: '<App/>'
})
5.App.vue
<template>
<div class="todo-container">
<div class="todo-wrap">
<!-- 传递函数属性(传递性)和绑定事件监听(用于父子组件) -->
<Header @addProject="addProject"/> <!-- 给标签对象绑定addProject事件监听 -->
<List :projects="projects" :deleteProject="deleteProject"/>
<todo-footer :projects="projects" :deleteAllComplete="deleteAllComplete"
:setSelect="setSelect"/>
</div>
</div>
</template>
<script>
import Header from './components/Header'
import List from './components/List'
import TodoFooter from './components/Footer'
import storageUtil from './utils/storageUtil'
export default {
name: 'App',
data () {
return { // 从localStorage中读取数据
// projects: JSON.parse(window.localStorage.getItem('project_key') || '[]')
projects: storageUtil.readProjects()
/*[
{
content: '吃饭',
complete: false,
},
{
content: '睡觉',
complete: true,
},
{
content: 'coding',
complete: false,
},
],*/
}
},
methods: {
addProject (project) { //添加project
this.projects.push(project)
},
deleteProject (index) { //根据index删除project
this.projects.splice(index,1)
},
deleteAllComplete () { //删除所有完成的任务
//将project中complete为true的过滤掉,留下false为一个新的数组,重新赋值
this.projects = this.projects.filter(project => !project.complete)
},
setSelect (isAllCheck) { //根据全选框值设置多选框是否勾选
this.projects.forEach(project => project.complete = isAllCheck)
}
},
watch: { // 监视
projects: {
deep: true, // 深度监视
/*handler: function (val) {
// 将projects最新的值的json数据保存到localStorage
// window.localStorage.setItem('project_key', JSON.stringify(val))
storageUtil.saveProjects(val)
}*/
handler: storageUtil.saveProjects
}
},
components: { Header, List, TodoFooter},
}
</script>
<style>
/*app*/
.todo-container {
600px;
margin: 0 auto;
}
.todo-container .todo-wrap {
padding: 10px;
border: 1px solid #ddd;
border-radius: 5px;
}
</style>
6.Header.vue
<template>
<div class="todo-header">
<input type="text" placeholder="请输入你的任务名称，按回车键确认"
@keyup.enter="addItem" v-model="content"/>
</div>
</template>
<script>
export default {
props: {
// addProject: Function
},
data () {
return {
content: '',
}
},
methods: {
addItem () {
// 1.检查输入的合法性
const content = this.content.trim()
if (!content) { // content默认不为空字符串,可不写 === ''
alert("不能为空")
return
}
// 2.根据输入生成一个project对象
const project = {
content: this.content,
complete: false
}
// 3.将对象添加到projects中
// this.addProject(project)
// 触发自定义事件:addProject; 只能用在父子组件,不能跨代通信
this.$emit('addProject',project)
// 4.清空输入
this.content = ''
}
}
}
</script>
<style>
/*header*/
.todo-header input {
560px;
height: 28px;
font-size: 14px;
border: 1px solid #ccc;
border-radius: 4px;
padding: 4px 7px;
}
.todo-header input:focus {
outline: none;
border-color: rgba(82, 168, 236, 0.8);
box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(82, 168, 236, 0.6);
}
</style>
7.List.vue
<template>
<ul class="todo-main">
<Item v-for="(project,index) in projects" :key="index" :project="project"
:index="index" :deleteProject="deleteProject"/>
</ul>
</template>
<script>
import Item from "../components/Item";
export default {
name: 'List',
components: {Item},
props: {
projects: Array,
deleteProject: Function
}
}
</script>
<style>
/*main*/
.todo-main {
margin-left: 0px;
border: 1px solid #ddd;
border-radius: 2px;
padding: 0px;
}
.todo-empty {
height: 40px;
line-height: 40px;
border: 1px solid #ddd;
border-radius: 2px;
padding-left: 5px;
margin-top: 10px;
}
</style>
8.Item.vue
<template>
<!-- onmouseover="" onmouseout="" -->
<li @mouseenter="handleEnter(true)" @mouseleave="handleEnter(false)" :style="{background: bgColor}">
<label>
<input type="checkbox" v-model="project.complete"/>
<span>{{project.content}}</span>
</label>
<button class="btn btn-danger" v-show="isShow" @click="deleteItem">删除</button>
</li>
</template>
<script>
export default {
name: 'Item',
props: {
project: Object,
index: Number,
deleteProject: Function
},
data () {
return {
bgColor: 'white',
isShow: false
}
},
methods: {
handleEnter (isEnter) {
if (isEnter) {
this.bgColor = '#aaaaaa'
this.isShow = true
}else {
this.bgColor = 'white'
this.isShow = false
}
},
deleteItem () {
const {deleteProject, project, index} = this
if (window.confirm(`确认删除${project.content}吗`)) {
deleteProject(index)
}
}
}
}
</script>
<style>
/*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;
}
</style>
9.Footer.vue
<template>
<div class="todo-footer">
<label>
<input type="checkbox" v-model="isAllCheck"/>
</label>
<span>
<span>已完成{{completeSize}}</span> / 全部{{projects.length}}
</span>
<button class="btn btn-danger" v-show="completeSize" @click="deleteAllComplete">清除已完成任务</button>
</div>
</template>
<script>
export default {
name: 'Footer',
props: {
projects: Array, //project数组
deleteAllComplete: Function, //清除已完成任务
setSelect: Function //根据全选框来设置其他所有多选框
},
computed: {
completeSize () {
// 遍历projects,初始化preTotal为0,若project.complete为true则加1,返回最终preTotal值
return this.projects.reduce((preTotal,project) => preTotal+(project.complete?1:0), 0)
},
isAllCheck: {
get(){ //获取多选框的值,当已完成数等于全部数量且已完成数大于0时,勾选(默认>0,可以不写)
return this.completeSize === this.projects.length && this.completeSize
},
set(value){ //监视多选框的值,value是当前多选框最新的值
this.setSelect(value)
}
}
}
}
</script>
<style>
/*footer*/
.todo-footer {
height: 40px;
line-height: 40px;
padding-left: 6px;
margin-top: 5px;
}
.todo-footer label {
display: inline-block;
margin-right: 20px;
cursor: pointer;
}
.todo-footer label input {
position: relative;
top: -1px;
vertical-align: middle;
margin-right: 5px;
}
.todo-footer button {
float: right;
margin-top: 5px;
}
</style>
扩展说明
- 案例中多处使用箭头函数,模板字符串,函数默认参数,扩展运算符,对象初始化简写等ES6新特性写法,可阅读 es6入门
- 关于vue的使用可参考vue官方教程和API: https://cn.vuejs.org/v2/guide/
- 若数字大于0(val>0),大于0可不写,默认大于0; 字符串为空时( !str),默认不为空字符串
- 关于Footer.vue中使用的
reduce()函数: 实现数组的累加操作
array.reduce(function(total, currentValue, currentIndex, arr), initialValue)
reduce函数可接受一个function函数以及一个initialValue(传入的初始值)的初始值。
其中function函数接受四个参数分别为total（每次计算的返回值），currentValue（当前数组的元素值），currentIndex（当前数组元素的索引值），arr（当前数组元素）