定義在default 外的變量, 全局變量可以使用

<template>
    <div>
        <div :class="someVarData"/> <!-- This is Ok -->
        <div :class="someVar"/> <!-- This is not Ok -->
    </div>
<template>
<script>
const someVar = "blah";
export default {
    data() {
        return {
            someVarData: "blahData",
        };
    },
    mounted() {
        const el = document.getElementById('myId');
        el.addEventListener('mouseenter', function () {
            console.log(someVar); // This is Ok
            console.log(this.someVarData); // This is not Ok
        });
    },
    beforeRouteEnter() { // <--- Vue-router's Navigation guard
        console.log(someVar); // This is Ok
        console.log(this.someVarData); // This is not Ok
    },
</script>

定義在default 內(nèi), 和 data外的數(shù)據(jù)
好像是computed 計算.
return 內(nèi)的應(yīng)該是渲染