How can I get toast-ui editor content?

I am a student studying. I think I'm doing it conceptually wrong.

I'm trying to use vue3 and type script And I'm going to use toast-ui editor.

I get some errors.

  1. refEditor.value.invoke is not a function

How can I get toast-ui editor content?

this is my code

  <div class="markup-tables flex">
    <va-card :title="$t('tables.stripedHoverable')">
        <div id="refEditor" ref="refEditor"></div>
        <br />
        <div class="row justify--end paginationButtons-left">
          <va-button class="mr-2 mb-2">List</va-button>
        <div class="row justify--end paginationButtons-right">
          <va-button class="mr-2 mb-2" @click="getHTML">Save</va-button>

<script lang="ts">
import '@toast-ui/editor/dist/toastui-editor.css'

import Editor from '@toast-ui/editor'
import { defineComponent, onMounted, ref } from 'vue'

import data from '@/data/tables/markup-table/data.json'

export default defineComponent({
  name: 'BoardWrite',
  setup() {
    const refEditor = ref(null)

    const getHTML = () => {
      console.log('getHTML test')
      let html = refEditor.value.invoke('getHtml')
      // ERROR 

    onMounted(() => {
      const editor = new Editor({
        el: refEditor.value,
        height: '700px',
        initialEditType: 'markdown',
        previewStyle: 'vertical',

    return {
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