1、挂载点、模板、实例之间的关系

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">
         
    </div>
     
    <script>
        <!--实例-->
        new Vue({
            el:"#app",<!--挂载点-->
            template:"<h1>xxx{{msg}}</h1>",<!--模板-->
            data:{
                msg:"hello world"
            }
        })
    </script>
  </body>
</html>

2、数据、事件和方法

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">
        <h1>hello {{msg}}</h1><!--插值表达式{{}}-->
        <h1 v-text="text_fasle"></h1><!-- v-text 不转义-->
        <div v-html="html_true"></div><!-- v-html 转义-->
        <div v-on:click="handleClick">{{content}}</div><!-- 点击事件 v-on:click-->
        <div @click="handleClick">{{content}}</div><!-- 点击事件 @click -->
    </div>
     
    <script>
        new Vue({
            el:"#app",
            data:{<!--数据-->
                msg:"world",
                text_fasle:"<h1>False</h1>",
                html_true:"<h1>True</h1>",
                content:"hello"
            },
            methods:{<!--方法定义-->
                handleClick:function(){
                    this.content="world"
                }
            }
        })
    </script>
  </body>
</html>

3、属性绑定、双向数据绑定和样式绑定

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">
        <div v-bind:title="title">hello world</div><!-- 属性绑定 v-bind:title -->
        <div :title="title">hello world</div><!-- 属性绑定 :title -->
         
        <input :value="content"/><!-- 单向数据绑定 即上面的属性绑定 -->
        <br>
        <input v-model="content"/><!-- 双向数据绑定 v-model -->
        <div>{{content}}</div>
    </div>
     
    <script>
        new Vue({
            el:"#app",
            data:{
                title:"this is hello world",
                content:"this is content"
            }
        })
    </script>
  </body>
</html>

样式绑定：

<!--对象语法-->
<div :class="{active:isActive}"></div>
<!--数组语法-->
<div :class="[activeClass,errorClass]"></div>

4、计算属性和侦听器

（1）为何需要计算属性？

表达式的计算逻辑可能会比较复杂，使用计算属性可以使模板内容更加简洁。

（2）计算属性与方法的区别

计算属性是基于它们的依赖进行缓存的；方法不存在缓存。

（3）侦听器

数据一旦发生变化就通知侦听器所绑定方法。

（4）侦听器的应用场景

数据变化时执行异步或开销较大的操作。

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">        
        姓：<input v-model="firstName"/>
        名：<input v-model="lastName"/>
        <div>{{fullName}}</div>
        <div>{{count}}</div>
    </div>
     
    <script>
        new Vue({
            el:"#app",
            data:{
                firstName:"",
                lastName:"",
                count:0
            },
            computed:{<!-- 计算属性 -->
                fullName:function(){
                    return this.firstName+this.lastName
                }
            },
            watch:{<!-- 侦听器 -->
                fullName:function(){
                    this.count++
                }
            }
        })
    </script>
  </body>
</html>

5、过滤器

（1）过滤器的作用是什么？

格式化数据，比如将字符串格式化为首字母大写，将日期格式化为指定的格式等。

（2）自定义过滤器

全局过滤器：

Vue.filter('过滤器名称',function (val) {
    //过滤器逻辑
})

局部过滤器：

filters:{
            capitalize:function () {   
            }
        }

（3）过滤器使用

<div>{{msg|upper}}</div>
<div :id="id|formatId"></div>

例子：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
</head>
<body>
<div id="app">
    <input type="text" v-model="msg">
    <div>{{msg|upper}}</div>
    <div :abc="msg|upper">测试数据</div>
    <div>{{msg|lower}}</div>
</div>
<script>
    Vue.filter('upper', function (val) {
        return val.charAt(0).toUpperCase() + val.slice(1)
    });
    new Vue({
        el: "#app",
        data: {
            msg: ''
        },
        filters: {
            lower: function (val) {
                return val.charAt(0).toLowerCase() + val.slice(1)
            }
        }
    })
</script>
</body>
</html>
  

6、v-if，v-show与v-for指令

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">
        <div v-if="showd">hello world</div><!-- v-if 判断 值为false直接将元素从dom中删除 -->
        <div v-show="showd">hello world</div><!-- v-show 判断 值为false将元素从dom中隐藏 -->
        <button @click="handleClick">toggle</button>
        <ul>
            <li v-for="(item,index) of items" :key="index">{{item,index}}</li>
            <!-- v-for 循环显示数据 其中:key提高渲染效率，唯一 -->
        </ul>
    </div>
     
    <script>
        new Vue({
            el:"#app",
            data:{
                showd:true,
                items:[1,2,3]
            },
            methods:{
                handleClick:function(){
                    this.showd=!this.showd
                }
            }
        })
    </script>
  </body>
</html>

7、案例：to-do-list开发

输入的内容可以在下面实时显示：

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <title>Vue Learning</title>
    <script src="./vue.js"></script>
  </head>
  <body>
    <div id="app">
        <div>
            <input v-model="inputValue"/>
            <button @click="handleClick">提交</button>
        </div>
        <ul>
            <li v-for="(item,index) of itemValues" :key="index">{{item}}</li>
        </ul>
    </div>
     
    <script>
        new Vue({
            el:"#app",
            data:{
                inputValue:"",
                itemValues:[]
            },
            methods:{
                handleClick:function(){
                    this.itemValues.push(this.inputValue)
                    this.inputValue=""
                }
            }
        })
    </script>
  </body>
</html>