vue组件化编程应用2

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:
在这里插入图片描述
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:
在这里插入图片描述
代码:

1.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>

2.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/>'
})

3.App.vue

<template>
  <div class="todo-container">
    <div class="todo-wrap">
      <Header :addProject="addProject"/>
      <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'

  export default {
    name: 'App',
    data () {
      return {
        projects: [
          {
            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)
      }
    },
    components: { Header, List, TodoFooter},

  }
</script>

<style>
  /*app*/
  .todo-container {
    width: 600px;
    margin: 0 auto;
  }
  .todo-container .todo-wrap {
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
  }
</style>

<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)
          // 4.清空输入
          this.content = ''
        }
      }
    }
</script>

<style>
  /*header*/
  .todo-header input {
    width: 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>

5.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>

6.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>

<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）