emptyness-dependency-free.js

export default class Emptyness {
  constructor(editor) {
    this.editor = editor;

  }

  init() {
    const doc = this.editor.model.document;
    const view = this.editor.ui.view.editable;
    
    if (!view) {
      return;
    }

    view.set( 'isEmpty', !documentHasContent(doc) );

    view.listenTo(doc, 'change:data', () => {
      view.set( 'isEmpty', !documentHasContent(doc) );
    } );

    if (view.isRendered === true) {
      return;
    }

    const bind = view.bindTemplate;

    view.extendTemplate( {
      attributes: {
        class: [
          bind.if( 'isEmpty', 'ck-editor__is-empty' )
        ]
      }
    } );
  }
}

function documentHasContent(doc) {
  return doc.model.hasContent(doc.getRoot());
}