遇到问题:需要定时刷新获取新的数据进行展示
解决方法:setInterval()定时刷新
备注:在vue项目中,我们该将刷新放在生命周期的mounted阶段。
代码:

       //定时刷新
        mounted() {
            if(this.timer){
                clearInterval(this.timer)
            }else{
                this.timer=setInterval(()=>{
                    //获取数据
                    this.loadData()
                },6000)
            }
        },
        //组件销毁时清除
        destroyed(){
            clearInterval(this.timer)
        },

首先看一下生命周期:
看一段代码:(可粘贴复制直接运行)

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script type="text/javascript" src="https://cdn.jsdelivr.net/vue/2.1.3/vue.js"></script>
</head>
<body>

<div id="app">
    <p>{{ message }}</p>
</div>

<script type="text/javascript">

    new Vue({
        el: '#app',
        data: {
            message: "weiqiujuan"
        },
        beforeCreate: function () {
            console.group('beforeCreate 创建前状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el); //undefined
            console.log("%c%s", "color:red", "data   : " + this.$data); //undefined
            console.log("%c%s", "color:red", "message: " + this.message)
        },
        created: function () {
            console.group('created 创建完毕状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el); //undefined
            console.log("%c%s", "color:red", "data   : " + this.$data); //已被初始化
            console.log("%c%s", "color:red", "message: " + this.message); //已被初始化
        },
        beforeMount: function () {
            console.group('beforeMount 挂载前状态===============》');
            console.log("%c%s", "color:red", "el     : " + (this.$el)); //已被初始化
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data); //已被初始化
            console.log("%c%s", "color:red", "message: " + this.message); //已被初始化
        },
        mounted: function () {
            console.group('mounted 挂载结束状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el); //已被初始化
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data); //已被初始化
            console.log("%c%s", "color:red", "message: " + this.message); //已被初始化
        },
        beforeUpdate: function () {
            console.group('beforeUpdate 更新前状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el);
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data);
            console.log("%c%s", "color:red", "message: " + this.message);
        },
        updated: function () {
            console.group('updated 更新完成状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el);
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data);
            console.log("%c%s", "color:red", "message: " + this.message);
        },
        beforeDestroy: function () {
            console.group('beforeDestroy 销毁前状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el);
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data);
            console.log("%c%s", "color:red", "message: " + this.message);
        },
        destroyed: function () {
            console.group('destroyed 销毁完成状态===============》');
            console.log("%c%s", "color:red", "el     : " + this.$el);
            console.log(this.$el);
            console.log("%c%s", "color:red", "data   : " + this.$data);
            console.log("%c%s", "color:red", "message: " + this.message)
        }
    })
</script>
</body>
</html>

结果:
在这里插入图片描述
是不是很清楚呀!

所以,我们的setInterval是放在mounted上的。
注: 使用setInterval时this指向的问题,如果我们直接使用this.timer=setInterval(function(){//要触发的函数})报错的,因为this指向的是window,但是我们要触发的函数是挂载在vm实例上的,所以需要使用箭头函数。

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