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<!DOCTYPE html>
<html lang="en">

<head>
    <title>watch Option 监控数据</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <script type="text/javascript" src="../assets/js/vue.js"></script>
</head>

<body>
    <h1>watch Option 监控数据</h1>
    <hr>
    <div id="app">
        <p>温度显示：{{wendu}}°</p>
        <p>穿衣建议：{{chuanyi}}</p>
        <p><button @click="shenggao">升高温度</button><button @click="jiangdi">降低温度</button></p>
    </div>

    <script type="text/javascript">
        var chuanyiarray = ["T恤短袖", "夹克长裙", "棉衣羽绒服"];

        

        var app = new Vue({
            el: '#app',
            data: {
                wendu: 14,
                chuanyi: "夹克长裙"
            },
            methods: {
                shenggao: function () {
                    this.wendu += 5;
                },
                jiangdi: function () {
                    this.wendu -= 5;
                }
            }
        })


        //在外部进行watch监控
        app.$watch("wendu",function(newVal, oldVal){
            if (newVal > 26) {
                        this.chuanyi = chuanyiarray[0];
                    } else if (newVal >= 0 && newVal <= 26) {
                        this.chuanyi = chuanyiarray[1];
                    } else {
                        this.chuanyi = chuanyiarray[2]
                    }
        })
    </script>
</body>

</html>
本项目引用的自定义外部资源

vue.js