diff --git a/area.js b/area.js
index f7b5e4c..ff12849 100644
--- a/area.js
+++ b/area.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported Tools, ToolNames, FontGenericFamilies, DrawingArea */
 
 /*
  * Copyright 2019 Abakkk
@@ -47,8 +48,7 @@ const SVG_DEBUG_EXTENDS = false;
 const TEXT_CURSOR_TIME = 600; // ms
 const GRID_TILES_HORIZONTAL_NUMBER = 30;
 
-const { Shapes, ShapeNames, Transformations, LineCapNames, LineJoinNames, FillRuleNames,
-        FontWeightNames, FontStyleNames, FontStretchNames, FontVariantNames } = Elements;
+const { Shapes, ShapeNames, Transformations, LineCapNames, LineJoinNames, FillRuleNames, FontWeightNames, FontStyleNames } = Elements;
 const Manipulations = { MOVE: 100, RESIZE: 101, MIRROR: 102 };
 const ManipulationNames = { 100: "Move", 101: "Resize", 102: "Mirror" };
 var Tools = Object.assign({}, Shapes, Manipulations);
diff --git a/elements.js b/elements.js
index c2214c7..e2b1acf 100644
--- a/elements.js
+++ b/elements.js
@@ -1,5 +1,3 @@
-/* jslint esversion: 6 */
-
 /*
  * Copyright 2019 Abakkk
  *
@@ -20,6 +18,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/* jslint esversion: 6 */
+/* exported Shapes, ShapeNames, Transformations, LineCapNames, LineJoinNames, FillRuleNames, FontWeightNames, FontStyleNames, getPangoFontFamilies, DrawingElement */
+
 const Cairo = imports.cairo;
 const Clutter = imports.gi.Clutter;
 const Lang = imports.lang;
@@ -43,8 +44,8 @@ var FillRuleNames = { 0: 'Nonzero', 1: 'Evenodd' };
 var FontWeightNames = Object.assign(reverseEnumeration(Pango.Weight), { 200: "Ultra-light", 350: "Semi-light", 600: "Semi-bold", 800: "Ultra-bold" });
 delete FontWeightNames[Pango.Weight.ULTRAHEAVY];
 var FontStyleNames = reverseEnumeration(Pango.Style);
-var FontStretchNames = reverseEnumeration(Pango.Stretch);
-var FontVariantNames = reverseEnumeration(Pango.Variant);
+const FontStretchNames = reverseEnumeration(Pango.Stretch);
+const FontVariantNames = reverseEnumeration(Pango.Variant);
 
 var getPangoFontFamilies = function() {
     return PangoCairo.font_map_get_default().list_families().map(fontFamily => fontFamily.get_name()).sort((a,b) => a.localeCompare(b));
diff --git a/extension.js b/extension.js
index d12d1bd..5f8607a 100644
--- a/extension.js
+++ b/extension.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported manager, init, enable, disable, setCursor */
 
 /*
  * Copyright 2019 Abakkk
@@ -45,7 +46,7 @@ const HIDE_TIMEOUT_LONG = 2500; // ms, default is 1500 ms
 const DRAWING_ACTION_MODE = Math.pow(2,14);
 const WRITING_ACTION_MODE = Math.pow(2,15);
 // use 'login-dialog-message-warning' class in order to get GS theme warning color (default: #f57900)
-var WARNING_COLOR_STYLE_CLASS_NAME = 'login-dialog-message-warning';
+const WARNING_COLOR_STYLE_CLASS_NAME = 'login-dialog-message-warning';
 
 var manager;
 
@@ -70,7 +71,7 @@ function disable() {
 // AreaManager assigns one DrawingArea per monitor (updateAreas()),
 // distributes keybinding callbacks to the active area
 // and handles stylesheet and monitor changes.
-var AreaManager = new Lang.Class({
+const AreaManager = new Lang.Class({
     Name: 'DrawOnYourScreenAreaManager',
 
     _init: function() {
diff --git a/files.js b/files.js
index 0001cc4..8315c20 100644
--- a/files.js
+++ b/files.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported Image, getImages, getJsons, getDateString */
 
 /*
  * Copyright 2019 Abakkk
diff --git a/helper.js b/helper.js
index d6704e9..7ed108d 100644
--- a/helper.js
+++ b/helper.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported DrawingHelper */
 
 /*
  * Copyright 2019 Abakkk
diff --git a/menu.js b/menu.js
index 666279a..b70ce5c 100644
--- a/menu.js
+++ b/menu.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported DrawingMenu */
 
 /*
  * Copyright 2019 Abakkk
@@ -59,6 +60,8 @@ const FULL_LINE_ICON_PATH = ICON_DIR.get_child('full-line-symbolic.svg').get_pat
 
 // 150 labels with font-family style take ~15Mo
 const FONT_FAMILY_STYLE = true;
+// use 'login-dialog-message-warning' class in order to get GS theme warning color (default: #f57900)
+const WARNING_COLOR_STYLE_CLASS_NAME = 'login-dialog-message-warning';
 
 const getActor = function(object) {
     return GS_VERSION < '3.33.0' ? object.actor : object;
@@ -308,18 +311,18 @@ var DrawingMenu = new Lang.Class({
                 target[targetProperty] = Math.max(Math.round(value * 50), 0);
                 label.set_text(target[targetProperty] + " px");
                 if (target[targetProperty] === 0)
-                    label.add_style_class_name(Extension.WARNING_COLOR_STYLE_CLASS_NAME);
+                    label.add_style_class_name(WARNING_COLOR_STYLE_CLASS_NAME);
                 else
-                    label.remove_style_class_name(Extension.WARNING_COLOR_STYLE_CLASS_NAME);
+                    label.remove_style_class_name(WARNING_COLOR_STYLE_CLASS_NAME);
             });
         } else {
             slider.connect('notify::value', () => {
                 target[targetProperty] = Math.max(Math.round(slider.value * 50), 0);
                 label.set_text(target[targetProperty] + " px");
                 if (target[targetProperty] === 0)
-                    label.add_style_class_name(Extension.WARNING_COLOR_STYLE_CLASS_NAME);
+                    label.add_style_class_name(WARNING_COLOR_STYLE_CLASS_NAME);
                 else
-                    label.remove_style_class_name(Extension.WARNING_COLOR_STYLE_CLASS_NAME);
+                    label.remove_style_class_name(WARNING_COLOR_STYLE_CLASS_NAME);
             });
         }
         
diff --git a/prefs.js b/prefs.js
index cbf1d1e..a92bb01 100644
--- a/prefs.js
+++ b/prefs.js
@@ -1,4 +1,5 @@
 /* jslint esversion: 6 */
+/* exported GLOBAL_KEYBINDINGS, INTERNAL_KEYBINDINGS, OTHER_SHORTCUTS, init, buildPrefsWidget */
 
 /*
  * Copyright 2019 Abakkk
@@ -100,10 +101,10 @@ var INTERNAL_KEYBINDINGS = {
 if (GS_VERSION < "3.36")
     delete INTERNAL_KEYBINDINGS['open-preferences'];
 
-function getKeyLabel(accel) {
+const getKeyLabel = function(accel) {
     let [keyval, mods] = Gtk.accelerator_parse(accel);
     return Gtk.accelerator_get_label(keyval, mods);
-}
+};
 
 var OTHER_SHORTCUTS = [
     { desc: "Draw", get shortcut() { return _("Left click"); } },