11.Computed Properties.html

<!--
    Computed 核心：
        1.把 属性 的计算放到 ViewModel 实例里做，避免HTML代码过于复杂
        2.Computed有缓存，相比于method方法，速度更快
        3.给Computed里的属性赋值时(如fullName = "xxx"),会触发fullName里的set函数。
-->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Computed</title>
    <script type="text/javascript"src="vue.js"></script>
</head>
<body>

    <div id="main">
        <p>{{ message }}</p>
        <p>{{ reversedMessage }}</p>    
    </div>
    <!--  两个例子的分割线   -->
        
    <div id="demo">{{ fullName }}</div>

</body>
<script type="text/javascript">
    var vm = new Vue({
        el:"#main",
        data:{
            message:"Hello"   
        },
        computed:{  
            reversedMessage:function(){
                // `this` points to the vm instance
                return this.message.split('').reverse().join('');
            }
        }
    });
/*------------------------两个例子的分割线--------------------------*/
    var vm = new Vue({
        el:"#demo",
        data:{
            firstName: 'Foo',
            lastName: 'Bar'
        },
        computed:{
            fullName:{
                //getter
                get:function(){
                    return this.firstName+' '+this.lastName;
                },
                set:function(newName){
                    var names = newName.split(' ');
                    this.firstName = names[0];
                    this.lastName = names[names.length - 1];
                }
            }
        }
    });
</script>
</html>