arcgis javascript api - Configurable Map Viewer (CMV) - average the values of the points

I have been able to select points and find the sum of the points. What I really need is to average the points. Here is my (acquired from someone else) code for finding the sum.

define([
'dojo/_base/declare',
'dijit/_WidgetBase',
'dijit/_TemplatedMixin',

'dijit/_WidgetsInTemplateMixin',
'esri/toolbars/draw',
'esri/InfoTemplate',
'esri/layers/FeatureLayer',
'esri/symbols/SimpleMarkerSymbol',
'esri/symbols/SimpleLineSymbol',
'esri/Color',
'esri/tasks/query',
'dijit/form/Button',
'dojo/_base/lang',

'dojo/on',
'dojo/_base/array',
'dojo/dom',
'dojo/text!./Select/templates/Select.html',
'xstyle/css!./Select/css/Select.css'
], function (declare, _WidgetBase, _TemplatedMixin, _WidgetsInTemplateMixin, Draw, InfoTemplate, FeatureLayer, SimpleMarkerSymbol, SimpleLineSymbol, Color, Query, Button, lang, on, arrayUtil, dom, SelectTemplate, css) {
    return declare([_WidgetBase, _TemplatedMixin, _WidgetsInTemplateMixin], {
        widgetsInTemplate: true,
        templateString: SelectTemplate,
        selectTools: null,


        postCreate: function () {
            this.selectTools = new Draw(this.map);

            this.selectQuery = new Query();

            on(this.selectTools, "DrawEnd", lang.hitch(this, function (geometry) {
                this.selectTools.deactivate();
                this.selectQuery.geometry = geometry;


                this.featureLayer.selectFeatures(this.selectQuery,
                FeatureLayer.SELECTION_NEW);
            }));
this.fieldsSelectionSymbol =
             new SimpleMarkerSymbol(SimpleMarkerSymbol.STYLE_CIRCLE, 10,
new SimpleLineSymbol(SimpleLineSymbol.STYLE_SOLID,
new Color([255,0,0]), 1),
new Color([0,255,0,0.25]));



            var infoTemplate = new InfoTemplate(this.title, this.content);

            this.featureLayer = new FeatureLayer(this.featureLayerURL,
            {
                mode: FeatureLayer.MODE_ONDEMAND,
                infoTemplate: infoTemplate,
                outFields: ["*"]
            });

            this.featureLayer.setDefinitionExpression(this.defExpress);

            this.featureLayer.setSelectionSymbol(this.fieldsSelectionSymbol);
            this.featureLayer.on("selection-complete", lang.hitch(this, 'sumGasProduction'));
            var clearMsg = this.clearSelectMsg;
            this.featureLayer.on("selection-clear", function () {
                dom.byId('messages').innerHTML = "" + clearMsg + "";
            });

            this.map.addLayer(this.featureLayer);

        },


        select: function () {
            this.selectTools.activate(Draw.EXTENT);
        },
        clearSelection: function () {
            this.featureLayer.clearSelection();
        },


        sumGasProduction: function (event) {

                        var productionSum = 0;
                        var sumField = this.fieldToSum;

                        arrayUtil.forEach(event.features, function (feature) {
                            productionSum += feature.attributes[sumField];

                        });
                        dom.byId('messages').innerHTML = "" + this.selectSumMsgPrefix + " " + productionSum + " " + this.selectSumUnits + ". ";
                    }
    });

});

Secondly my clear selection button is not working.

---

Here is my code for clear selection:

I have no idea how to get the average. I was trying to use what you said in another answer but I could not figure it out. I have found an example that does find the average

https://developers.arcgis.com/javascript/jssamples/query_bypoly.html

      function average(fset, att) {
    var features = fset.features;
    var sum = 0;
    var featuresLength = features.length;
    for (var x = 0; x < featuresLength; x++) {
      sum = sum + features[x].attributes[att];

    }
    return Math.round(sum/featuresLength);
  }

Answer

You did not provide the template HTML for your button so this is just a guess as to the issue. Your button needs an 'onClick' event to execute your 'clearSelection' method. Something like this:

data-dojo-attach-event="onClick:clearSelection"

To display an average instead of a sum, you can use the original method you posted with a slight variation:

avgGasProduction: function (event) {
    var productionSum = 0, productionAvg = 0;

    var sumField = this.fieldToSum;

    arrayUtil.forEach(event.features, function (feature) {
        productionSum += feature.attributes[sumField];
    });

    if (event.features && event.features.length > 0) {
        productionAvg = Math.round(productionSum / event.features.length)
    }


    dom.byId('messages').innerHTML = "" + this.selectSumMsgPrefix + " " + productionAvg + " " + this.selectSumUnits + ". ";
}