vue属性监听watch，监听对象中属性的变化

watch和data、methods等同级

watch两个参数（newValue,odlValue）  分别为新数据和旧数据

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title></title>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
    <script src="https://unpkg.com/axios/dist/axios.min.js"></script>
</head>
<body>
    <div id='app'>
        <input type="text" v-model='msg'>
    </div>


    <script>
    const vm = new Vue({
        el: '#app',
        data: {
            msg:'111'
        },
        methods: {
        },
        // 属性监听
        watch:{
            // 两个参数（新数据，旧数据）
            msg(newValue,oldvalue){
                // 监听input框变化，分别打印新数据和旧数据
                console.log(newValue);
                console.log(oldvalue);
            }
        }
    })
    </script>
</body>
</html>

 监听对象中单个属性的变化

watch:{
          "drawer.drawer": {
            handler(newValue, oldValue) {
              console.log("单个属性监听", newValue, oldValue);
            }
          },

 

posted @ 2021-09-20 10:33  从入门到入土  阅读(180)  评论(0)    收藏  举报