md/src/App.vue

<template>
    <transition name="fade" v-if="loading">
        <loading />
    </transition>
    <codemirror-editor v-else />
</template>

<script>
import Loading from './components/Loading'
import CodemirrorEditor from './view/CodemirrorEditor'
export default {
    name: 'App',
    components: {
        Loading,
        CodemirrorEditor
    },
    data() {
        return {
            loading: true
        }
    },
    mounted() {
        setTimeout(() => {
            this.loading = false
        }, 100);
    }
}

</script>

<style lang="scss" scoped>
.fade-enter,.fade-leave-to{
    opacity: 0;
}
.fade-enter-to,.fade-leave{
    opacity: 1;
}
.fade-enter-active,.fade-leave-active{
    transition: all 2s;
}
</style>