The simplest possible Dojo widget-based editing component for Episerver.

Editor.js

define(
    ["dojo/_base/declare", "dojo/ready", "dijit/_Widget", "dijit/_TemplatedMixin", "epi/epi"],
    function (declare, ready, _Widget, _TemplatedMixin, epi) {
        return declare(
            [_Widget, _TemplatedMixin],
            {
                templateString: '<textarea data-dojo-attach-event="onchange:_onChange"></textarea>',

                constructor: function () {
                    ready(this, function () {
                        this.set('value', this.value);
                    });
                },

                _onChange: function (event) {
                    if (!epi.areEqual(this.get('value'), event.target.value)) {
                        this.set('value', event.target.value);
                        this.onChange(this.value);
                    }
                }
            }
        )
    }
);