VUE生命周期函数

<!DOCTYPE html>
<html>

<head>
    <title></title>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/vue/2.1.3/vue.js"></script>
</head>

<body>

    <div >
        <p>{{ message }}</p>
        <button @click="btn">改变按钮</button>
    </div>

    <script type="text/javascript">
        var app = new Vue({
            el: '#app',
            data: {
                message: "xuxiao is boy"
            },
            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) //undefined 
            },
            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)
            },
            methods: {
                btn: function() {
                    this.message = "change"
                }
            }
        })
    </script>
</body>

</html>