生命周期

1、案例1
<!DOCTYPE html>
<html>

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>生命周期</title>
</head>

<body>
    <div id="app">
        <button @click="clickFunc">销毁VUE实例</button>
        <p v-show="showFlag">测试VUE生命周期</p>
    </div>
    <script src="../js/vue.js" type="text/javascript"></script>
    <script>
        const vm = new Vue({
            el: "#app",
            data: {
                intervalId: null,
                showFlag: true
            },
            beforeCreate() {//执行一次
                console.info("beforeCreate...");
            },
            created() {//执行一次
                this.intervalId = setInterval(() => {
                    this.showFlag = !this.showFlag;
                    console.info("定时器还在执行...");
                }, 1000);
                console.info("created...");
            },
            beforeMount() {//执行一次
                console.info("beforeMount...");
            },
            mounted() {//执行一次
                console.info("mounted...");
            },
            beforeUpdate() { //会执行N次
                console.info("beforeUpdate...");
            },
            updated() { //会执行N次
                console.info("updated...");
            },
            beforeDestroy() {//执行一次
                //销毁VM实例前关闭定时器
                clearInterval(this.intervalId);
                console.info("beforeDestroy...");
            },
            destroyed() {//执行一次
                console.info("destroyed...");
            },
            methods: {
                clickFunc() {
                    //销毁VM实例
                    this.$destroy();
                }
            }
        });
    </script>
</body>

</html>