Adding a “show html” button in Quill (Wysiwyg).

Wysiwyg.vue

<template>
  <div>
    <vue-editor v-model="content" ref="editor" :editor-options="toolbarOptions" @text-change="updateValue" useCustomImageHandler @imageAdded="uploadImage"></vue-editor>
  </div>
</template>

<script>
import Vue from "vue";
import axios from 'axios'
let VueEditor, Quill;
if (process.browser) {
  VueEditor = require("vue2-editor").VueEditor;
  Quill = require("vue2-editor").Quill;
}

export default {
  props: ["value"],
  data() {
    let toolbarOptions = {
      modules: {
        toolbar: {
          container: [
            [{ font: [] }],
            [{ header: [false, 1, 2, 3, 4, 5, 6] }],
            ["bold", "italic", "underline", "strike"],
            [{ align: [] }],
            ["blockquote", "code-block"],
            [{ list: "ordered" }, { list: "bullet" }, { list: "check" }],
            [{ indent: "-1" }, { indent: "+1" }],
            [{ color: [] }, { background: [] }],
            ["link", "image", "video"],
            ["clean"],
            ["showHtml"]
          ],
          handlers: {
            showHtml: () => {
              if (this.txtArea.style.display === "") {
                const html = this.txtArea.value;
              if (html === '<p><br/></p>') {
                this.html = null;
              } else {
                this.html = html.replace(new RegExp('<p><br/>', 'g'), '<p>')
              }
                this.quill.pasteHTML(html);
              }
              this.txtArea.style.display =
                this.txtArea.style.display === "none" ? "" : "none";
            }
          }
        }
      }
    };
    return {
      toolbarOptions,
      content: "",
      rawContent: ""
    };
  },
  components: {
    VueEditor
  },
  mounted() {
    this.quill = this.$refs.editor.quill;
    this.txtArea = document.createElement("textarea");
    this.txtArea.style.cssText =
      "width: 100%;margin: 0px;background: rgb(29, 29, 29);box-sizing: border-box;color: rgb(204, 204, 204);font-size: 15px;outline: none;padding: 20px;line-height: 24px;font-family: Consolas, Menlo, Monaco, &quot;Courier New&quot;, monospace;position: absolute;top: 0;bottom: 0;border: none;display:none;resize: none;";
    
    const htmlEditor = this.quill.addContainer("ql-custom");
    htmlEditor.appendChild(this.txtArea);
    
    this.quill.on("text-change", (delta, oldDelta, source) => {
      var html = this.quill.getHTML();
      this.txtArea.value = html;
    });

    this.content = this.value;
  },
  watch: {
    content() {
      this.rawContent = this.content;
    },
    rawContent() {
      this.content = this.rawContent;
    }
  },
  methods: {
    updateValue () {
      this.$emit('input', this.$refs.editor.quill.getHTML())
    },
    async uploadImage(file, Editor, cursorLocation, resetUploader) {
      const fd = new window.FormData()
			fd.append('file', file)
			fd.append('upload_preset', 'vxjellmt')
			fd.append('folder', 'outorah')

      const { data } = await axios.post("https://api.cloudinary.com/v1_1/ouinternal/image/upload", fd, {
				headers: {
					'Content-Type': 'multipart/form-data'
				}
			})
      
      let url = `https://res.cloudinary.com/ouinternal/image/upload/${data.public_id}`
      Editor.insertEmbed(cursorLocation, "image", url)
      resetUploader()
    }
  }
};
</script>

<style>
.quillWrapper {
  line-height: normal;
}
span.ql-formats:first-child > .ql-picker,
span.ql-header.ql-picker {
  border: 1px solid #ddd;
  display: flex;
  height: 100%;
  padding: 2px;
  box-shadow: inset 0 1px 1px -1px rgba(0, 0, 0, 0.2);
  background: white;
}
.ql-toolbar.ql-snow {
  border: 1px solid #eee !important;
  background: #f5f5f58c;
  border-radius: 0 0 4px 4px;
}
.ql-container.ql-snow {
  background: #fff;
  width: 100%;
  min-height: 200px;
  border-top: 0 !important;
  border-left: 1px solid #ddd !important;
  border-right: 1px solid #ddd !important;
  border-bottom: 1px solid #ddd !important;
}
.ql-stroke {
  stroke: #555d66 !important;
}
.ql-snow .ql-fill,
.ql-snow .ql-stroke.ql-fill {
  fill: #555d66 !important;
}
.ql-editor.ql-blank::before {
  color: rgba(0, 0, 0, 0.3) !important;
  font-style: normal !important;
}
.ql-editor {
  min-height: 300px;
  font-size: 15px;
  font-family: Arial;
  line-height: 24px;
}
.ql-container {
  font-size: 15px;
  font-family: Arial;
  line-height: 24px;
}
.ql-container p {
  margin-bottom: 10px;
}
.ql-formats button:hover,
.ql-formats .ql-picker:hover {
  background: #abd4ff73 !important;
}
.ql-formats .ql-header.ql-picker:hover,
.ql-formats .ql-font.ql-picker:hover {
  background: white !important;
  border-color: #b4b9be;
}
.ql-picker-label {
  display: flex !important;
}
.ql-align.ql-picker.ql-icon-picker .ql-picker-label {
  display: block !important;
}

.ql-showHtml:after {
  content: "[source]";
}
button.ql-showHtml {
  width: 100% !important;
}

</style>

Thank you for this reference! Really appreciate it.