grapesjs/src/style_manager/model/Layer.js

import Backbone from 'backbone';
import Properties from './Properties';

export default Backbone.Model.extend({
  defaults: {
    index: '',
    value: '',
    values: {},
    active: false,
    preview: false,
    properties: [],
  },

  initialize() {
    const prp = this.get('properties');
    var value = this.get('value');
    this.set('properties', prp instanceof Properties ? prp : new Properties(prp));
    const props = this.get('properties');
    props.forEach(this.onPropAdd, this);
    this.listenTo(props, 'add', this.onPropAdd);

    // If there is no value I'll try to get it from values
    // I need value setted to make preview working
    if (!value) {
      var val = '';
      var values = this.get('values');

      for (var prop in values) {
        val += ' ' + values[prop];
      }

      this.set('value', val.trim());
    }
  },

  getValues() {
    return this.get('values');
  },

  getIndex() {
    const coll = this.collection;
    return coll ? coll.indexOf(this) : -1;
  },

  onPropAdd(prop) {
    const coll = this.collection;
    prop.parent = coll && coll.property;
  },

  /**
   * Get property at some index
   * @param  {Number} index
   * @return {Object}
   */
  getPropertyAt(index) {
    return this.get('properties').at(index);
  },

  getPropertyValue(property) {
    let result = '';
    this.get('properties').each(prop => {
      if (prop.get('property') == property) {
        result = prop.getFullValue();
      }
    });
    return result;
  },

  getFullValue() {
    let result = [];
    this.get('properties').each(prop => result.push(prop.getFullValue()));
    return result.join(' ').trim();
  },
});