diff --git a/src/datasource-zabbix/add-metric-function.directive.js b/src/datasource-zabbix/add-metric-function.directive.js
index 88448e5..795a254 100644
--- a/src/datasource-zabbix/add-metric-function.directive.js
+++ b/src/datasource-zabbix/add-metric-function.directive.js
@@ -3,10 +3,12 @@ import _ from 'lodash';
 import $ from 'jquery';
 import * as metricFunctions from './metricFunctions';
 
-/** @ngInject */
 angular
   .module('grafana.directives')
-  .directive('addMetricFunction', function($compile) {
+  .directive('addMetricFunction',
+
+  /** @ngInject */
+  function($compile) {
     var inputTemplate = '<input type="text"'+
                           ' class="gf-form-input"' +
                           ' spellcheck="false" style="display:none"></input>';
diff --git a/src/datasource-zabbix/config.controller.js b/src/datasource-zabbix/config.controller.js
index 0160ac9..703c13c 100644
--- a/src/datasource-zabbix/config.controller.js
+++ b/src/datasource-zabbix/config.controller.js
@@ -9,6 +9,7 @@ const defaultConfig = {
 };
 
 export class ZabbixDSConfigController {
+
   /** @ngInject */
   constructor($scope, $injector, datasourceSrv) {
     this.datasourceSrv = datasourceSrv;
@@ -24,5 +25,3 @@ export class ZabbixDSConfigController {
     });
   }
 }
-
-ZabbixDSConfigController.templateUrl = 'datasource-zabbix/partials/config.html';
diff --git a/src/datasource-zabbix/datasource.js b/src/datasource-zabbix/datasource.js
index 4a91e31..972a849 100644
--- a/src/datasource-zabbix/datasource.js
+++ b/src/datasource-zabbix/datasource.js
@@ -6,11 +6,10 @@ import * as metricFunctions from './metricFunctions';
 import * as c from './constants';
 import dataProcessor from './dataProcessor';
 import responseHandler from './responseHandler';
-import './zabbixAlerting.service.js';
 import { Zabbix } from './zabbix/zabbix';
-import {ZabbixAPIError} from './zabbix/connectors/zabbix_api/zabbixAPICore';
+import { ZabbixAPIError } from './zabbix/connectors/zabbix_api/zabbixAPICore';
 
-class ZabbixAPIDatasource {
+export class ZabbixDatasource {
 
   /** @ngInject */
   constructor(instanceSettings, templateSrv, alertSrv, dashboardSrv, backendSrv, datasourceSrv, zabbixAlertingSrv) {
@@ -96,7 +95,7 @@ class ZabbixAPIDatasource {
 
     // Create request for each target
     let promises = _.map(options.targets, t => {
-      // Don't request undefined and hidden targets
+      // Don't request for hidden targets
       if (t.hide) {
         return [];
       }
@@ -111,7 +110,7 @@ class ZabbixAPIDatasource {
       // Apply Time-related functions (timeShift(), etc)
       let timeFunctions = bindFunctionDefs(target.functions, 'Time');
       if (timeFunctions.length) {
-        const [time_from, time_to] = sequence(timeFunctions)([timeFrom, timeTo]);
+        const [time_from, time_to] = utils.sequence(timeFunctions)([timeFrom, timeTo]);
         timeFrom = time_from;
         timeTo = time_to;
       }
@@ -124,8 +123,8 @@ class ZabbixAPIDatasource {
         // Migrate old targets
         target = migrations.migrate(target);
 
-        // Don't request undefined and hidden targets
-        if (target.hide || !target.group || !target.host || !target.item) {
+        // Don't request undefined targets
+        if (!target.group || !target.host || !target.item) {
           return [];
         }
 
@@ -167,9 +166,7 @@ class ZabbixAPIDatasource {
       itemtype: 'num'
     };
     return this.zabbix.getItemsFromTarget(target, getItemOptions)
-    .then(items => {
-      return this.queryNumericDataForItems(items, target, timeRange, useTrends, options);
-    });
+    .then(items => this.queryNumericDataForItems(items, target, timeRange, useTrends, options));
   }
 
   /**
@@ -208,19 +205,19 @@ class ZabbixAPIDatasource {
 
     // Apply transformation functions
     timeseries_data = _.cloneDeep(_.map(timeseries_data, timeseries => {
-      timeseries.datapoints = sequence(transformFunctions)(timeseries.datapoints);
+      timeseries.datapoints = utils.sequence(transformFunctions)(timeseries.datapoints);
       return timeseries;
     }));
 
     // Apply filter functions
     if (filterFunctions.length) {
-      timeseries_data = sequence(filterFunctions)(timeseries_data);
+      timeseries_data = utils.sequence(filterFunctions)(timeseries_data);
     }
 
     // Apply aggregations
     if (aggregationFunctions.length) {
       let dp = _.map(timeseries_data, 'datapoints');
-      dp = sequence(aggregationFunctions)(dp);
+      dp = utils.sequence(aggregationFunctions)(dp);
 
       let aggFuncNames = _.map(metricFunctions.getCategories()['Aggregate'], 'name');
       let lastAgg = _.findLast(target.functions, func => {
@@ -234,7 +231,7 @@ class ZabbixAPIDatasource {
     }
 
     // Apply alias functions
-    _.forEach(timeseries_data, sequence(aliasFunctions));
+    _.forEach(timeseries_data, utils.sequence(aliasFunctions));
 
     // Apply Time-related functions (timeShift(), etc)
     // Find timeShift() function and get specified trend value
@@ -648,7 +645,7 @@ function formatMetric(metricObj) {
  * template variables, for example
  * /CPU $cpu_item.*time/ where $cpu_item is system,user,iowait
  */
-function zabbixTemplateFormat(value) {
+export function zabbixTemplateFormat(value) {
   if (typeof value === 'string') {
     return utils.escapeRegex(value);
   }
@@ -680,17 +677,6 @@ function replaceTemplateVars(templateSrv, target, scopedVars) {
   return replacedTarget;
 }
 
-// Apply function one by one:
-// sequence([a(), b(), c()]) = c(b(a()));
-function sequence(funcsArray) {
-  return function(result) {
-    for (var i = 0; i < funcsArray.length; i++) {
-      result = funcsArray[i].call(this, result);
-    }
-    return result;
-  };
-}
-
 function filterEnabledTargets(targets) {
   return _.filter(targets, target => {
     return !(target.hide || !target.group || !target.host || !target.item);
@@ -709,8 +695,6 @@ function getTriggerThreshold(expression) {
   }
 }
 
-export {ZabbixAPIDatasource, zabbixTemplateFormat};
-
 // Fix for backward compatibility with lodash 2.4
 if (!_.includes) {_.includes = _.contains;}
 if (!_.keyBy) {_.keyBy = _.indexBy;}
diff --git a/src/datasource-zabbix/metric-function-editor.directive.js b/src/datasource-zabbix/metric-function-editor.directive.js
index e0d35b4..b87ff90 100644
--- a/src/datasource-zabbix/metric-function-editor.directive.js
+++ b/src/datasource-zabbix/metric-function-editor.directive.js
@@ -2,10 +2,14 @@ import angular from 'angular';
 import _ from 'lodash';
 import $ from 'jquery';
 
-/** @ngInject */
+const DOCS_FUNC_REF_URL = 'http://docs.grafana-zabbix.org/reference/functions/';
+
 angular
   .module('grafana.directives')
-  .directive('metricFunctionEditor', function($compile, templateSrv) {
+  .directive('metricFunctionEditor',
+
+  /** @ngInject */
+  function($compile, templateSrv) {
 
     var funcSpanTemplate = '<a ng-click="">{{func.def.name}}</a><span>(</span>';
     var paramTemplate = '<input type="text" style="display:none"' +
@@ -221,7 +225,7 @@ angular
             }
 
             if ($target.hasClass('fa-question-circle')) {
-              var docSite = "http://docs.grafana-zabbix.org/reference/functions/";
+              var docSite = DOCS_FUNC_REF_URL;
               window.open(docSite + '#' + funcDef.name.toLowerCase(),'_blank');
               return;
             }
diff --git a/src/datasource-zabbix/module.js b/src/datasource-zabbix/module.js
index 248ba77..49b1e3e 100644
--- a/src/datasource-zabbix/module.js
+++ b/src/datasource-zabbix/module.js
@@ -1,7 +1,10 @@
-import {loadPluginCss} from 'app/plugins/sdk';
-import {ZabbixAPIDatasource} from './datasource';
-import {ZabbixQueryController} from './query.controller';
-import {ZabbixDSConfigController} from './config.controller';
+import { loadPluginCss } from 'app/plugins/sdk';
+import { ZabbixDatasource } from './datasource';
+import { ZabbixQueryController } from './query.controller';
+import { ZabbixDSConfigController } from './config.controller';
+import './zabbixAlerting.service.js';
+import './add-metric-function.directive';
+import './metric-function-editor.directive';
 
 loadPluginCss({
   dark: 'plugins/alexanderzobnin-zabbix-app/css/grafana-zabbix.dark.css',
@@ -14,8 +17,11 @@ ZabbixQueryOptionsController.templateUrl = 'datasource-zabbix/partials/query.opt
 class ZabbixAnnotationsQueryController {}
 ZabbixAnnotationsQueryController.templateUrl = 'datasource-zabbix/partials/annotations.editor.html';
 
+ZabbixQueryController.templateUrl = 'datasource-zabbix/partials/query.editor.html';
+ZabbixDSConfigController.templateUrl = 'datasource-zabbix/partials/config.html';
+
 export {
-  ZabbixAPIDatasource as Datasource,
+  ZabbixDatasource as Datasource,
   ZabbixDSConfigController as ConfigCtrl,
   ZabbixQueryController as QueryCtrl,
   ZabbixQueryOptionsController as QueryOptionsCtrl,
diff --git a/src/datasource-zabbix/query.controller.js b/src/datasource-zabbix/query.controller.js
index 733fdd8..ca7b5be 100644
--- a/src/datasource-zabbix/query.controller.js
+++ b/src/datasource-zabbix/query.controller.js
@@ -1,13 +1,10 @@
-import {QueryCtrl} from 'app/plugins/sdk';
+import { QueryCtrl } from 'app/plugins/sdk';
 import _ from 'lodash';
 import * as c from './constants';
 import * as utils from './utils';
 import * as metricFunctions from './metricFunctions';
 import * as migrations from './migrations';
 
-import './add-metric-function.directive';
-import './metric-function-editor.directive';
-
 export class ZabbixQueryController extends QueryCtrl {
 
   // ZabbixQueryCtrl constructor
@@ -333,6 +330,3 @@ export class ZabbixQueryController extends QueryCtrl {
     this.targetChanged();
   }
 }
-
-// Set templateUrl as static property
-ZabbixQueryController.templateUrl = 'datasource-zabbix/partials/query.editor.html';
diff --git a/src/datasource-zabbix/specs/datasource.spec.js b/src/datasource-zabbix/specs/datasource.spec.js
index 697c982..3425465 100644
--- a/src/datasource-zabbix/specs/datasource.spec.js
+++ b/src/datasource-zabbix/specs/datasource.spec.js
@@ -1,7 +1,7 @@
 import _ from 'lodash';
 import Q, { Promise } from "q";
-import {Datasource} from "../module";
-import {zabbixTemplateFormat} from "../datasource";
+import { Datasource } from "../module";
+import { zabbixTemplateFormat } from "../datasource";
 
 describe('ZabbixDatasource', () => {
   let ctx = {};
diff --git a/src/datasource-zabbix/utils.js b/src/datasource-zabbix/utils.js
index 4d2d704..efc8ad2 100644
--- a/src/datasource-zabbix/utils.js
+++ b/src/datasource-zabbix/utils.js
@@ -227,6 +227,19 @@ export function callOnce(func, promiseKeeper) {
   };
 }
 
+/**
+ * Apply function one by one: `sequence([a(), b(), c()]) = c(b(a()))`
+ * @param {*} funcsArray functions to apply
+ */
+export function sequence(funcsArray) {
+  return function(result) {
+    for (var i = 0; i < funcsArray.length; i++) {
+      result = funcsArray[i].call(this, result);
+    }
+    return result;
+  };
+}
+
 // Fix for backward compatibility with lodash 2.4
 if (!_.includes) {
   _.includes = _.contains;
diff --git a/src/datasource-zabbix/zabbix/connectors/dbConnector.js b/src/datasource-zabbix/zabbix/connectors/dbConnector.js
index 1974d35..6699b45 100644
--- a/src/datasource-zabbix/zabbix/connectors/dbConnector.js
+++ b/src/datasource-zabbix/zabbix/connectors/dbConnector.js
@@ -2,6 +2,10 @@ import _ from 'lodash';
 
 const NOT_IMPLEMENTED = 'Method should be implemented in subclass of DBConnector';
 
+/**
+ * Base class for external history database connectors. Subclasses should implement `getHistory()`, `getTrends()` and
+ * `testDataSource()` methods, which describe how to fetch data from source other than Zabbix API.
+ */
 export default class DBConnector {
   constructor(options, backendSrv, datasourceSrv) {
     this.backendSrv = backendSrv;
@@ -24,14 +28,23 @@ export default class DBConnector {
     }
   }
 
+  /**
+   * Send test request to datasource in order to ensure it's working.
+   */
   testDataSource() {
     throw NOT_IMPLEMENTED;
   }
 
+  /**
+   * Get history data from external sources.
+   */
   getHistory() {
     throw NOT_IMPLEMENTED;
   }
 
+  /**
+   * Get trends data from external sources.
+   */
   getTrends() {
     throw NOT_IMPLEMENTED;
   }