vue9 计算属性 computed

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>智能社——http://www.zhinengshe.com</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <style>

    </style>
    <script src="vue.js"></script>
    <script>

    </script>
</head>
<body>
    <div id="box">
        {{a}}
        <br>
       {{b}}
    </div>
    <script>
        var vm=new Vue({
            el:'#box',
            data:{
                a:1
            },
            computed:{
                b:function(){//默认调用get
                    //业务逻辑代码
                    return 2;
                }
            }
        });

        console.log(vm.a);
    </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>智能社——http://www.zhinengshe.com</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <style>

    </style>
    <script src="vue.js"></script>
    <script>

    </script>
</head>
<body>
    <div id="box">
        {{a}}
        <br>
        {{b}}
    </div>
    <script>
        var vm=new Vue({
            el:'#box',
            data:{
                a:1
            },
            computed:{
                b:function(){
                    //业务逻辑代码
                    return this.a+1;
                }
            }
        });

        document.onclick=function(){
            vm.a=101;
        };
    </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>智能社——http://www.zhinengshe.com</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <style>

    </style>
    <script src="vue.js"></script>
    <script>

    </script>
</head>
<body>
    <div id="box">
        {{a}}
        <br>
        {{b}}
    </div>
    <script>
        var vm=new Vue({
            el:'#box',
            data:{
                a:1
            },
            computed:{//computed里面可以放置一些业务逻辑代码，一定记得return
                b:{
                    get:function(){
                        return this.a+2;
                    },
                    set:function(val){
                        this.a=val;
                    }
                }
            }
        });

        document.onclick=function(){
            vm.b=10;
        };
    </script>
</body>
</html>