_updateDomField () {
    const domField = this.dom.field
    if (domField) {
      const tooltip = makeFieldTooltip(this.schema, this.editor.options.language)
      if (tooltip) {
        domField.title = tooltip
      }

      // make background color lightgray when empty
      const isEmpty = (String(this.field) === '' && this.parent && this.parent.type !== 'array')
      if (isEmpty) {
        addClassName(domField, 'jsoneditor-empty')
      } else {
        removeClassName(domField, 'jsoneditor-empty')
      }

      // highlight when there is a search result
      if (this.searchFieldActive) {
        addClassName(domField, 'jsoneditor-highlight-active')
      } else {
        removeClassName(domField, 'jsoneditor-highlight-active')
      }
      if (this.searchField) {
        addClassName(domField, 'jsoneditor-highlight')
      } else {
        removeClassName(domField, 'jsoneditor-highlight')
      }

      // strip formatting from the contents of the editable div
      stripFormatting(domField)
    }
  }
Update dom field:
- the text color of the field, depending on the text
- the height of the field, depending on the width
- background color in case it is empty
@private