diff --git a/src/ol/geom/linestring.js b/src/ol/geom/linestring.js
index 7305604068..3aeb2980ff 100644
--- a/src/ol/geom/linestring.js
+++ b/src/ol/geom/linestring.js
@@ -2,6 +2,7 @@ goog.provide('ol.geom.LineString');
 
 goog.require('goog.array');
 goog.require('goog.asserts');
+goog.require('ol');
 goog.require('ol.extent');
 goog.require('ol.geom.GeometryLayout');
 goog.require('ol.geom.GeometryType');
@@ -148,7 +149,8 @@ ol.geom.LineString.prototype.getCoordinateAtM = function(m, opt_extrapolate) {
       this.layout != ol.geom.GeometryLayout.XYZM) {
     return null;
   }
-  var extrapolate = opt_extrapolate ? opt_extrapolate : false;
+  var extrapolate = ol.isDef(opt_extrapolate) ?
+      /** @type {boolean} */ (opt_extrapolate) : false;
   return ol.geom.flat.lineStringCoordinateAtM(this.flatCoordinates, 0,
       this.flatCoordinates.length, this.stride, m, extrapolate);
 };
diff --git a/src/ol/interaction/dragrotateandzoominteraction.js b/src/ol/interaction/dragrotateandzoominteraction.js
index f764286ce3..c0c8f6df8d 100644
--- a/src/ol/interaction/dragrotateandzoominteraction.js
+++ b/src/ol/interaction/dragrotateandzoominteraction.js
@@ -1,6 +1,7 @@
 goog.provide('ol.interaction.DragRotateAndZoom');
 
 goog.require('goog.math.Vec2');
+goog.require('ol');
 goog.require('ol.ViewHint');
 goog.require('ol.events.ConditionType');
 goog.require('ol.events.condition');
@@ -89,17 +90,17 @@ ol.interaction.DragRotateAndZoom.handleDragEvent_ = function(mapBrowserEvent) {
   var magnitude = delta.magnitude();
   var view = map.getView();
   map.render();
-  if (this.lastAngle_ !== undefined) {
+  if (ol.isDef(this.lastAngle_)) {
     var angleDelta = theta - this.lastAngle_;
     ol.interaction.Interaction.rotateWithoutConstraints(
         map, view, view.getRotation() - angleDelta);
   }
   this.lastAngle_ = theta;
-  if (this.lastMagnitude_ !== undefined) {
+  if (ol.isDef(this.lastMagnitude_)) {
     var resolution = this.lastMagnitude_ * (view.getResolution() / magnitude);
     ol.interaction.Interaction.zoomWithoutConstraints(map, view, resolution);
   }
-  if (this.lastMagnitude_ !== undefined) {
+  if (ol.isDef(this.lastMagnitude_)) {
     this.lastScaleDelta_ = this.lastMagnitude_ / magnitude;
   }
   this.lastMagnitude_ = magnitude;
diff --git a/src/ol/interaction/dragrotateinteraction.js b/src/ol/interaction/dragrotateinteraction.js
index d5815a08c8..c7a97d752b 100644
--- a/src/ol/interaction/dragrotateinteraction.js
+++ b/src/ol/interaction/dragrotateinteraction.js
@@ -1,5 +1,6 @@
 goog.provide('ol.interaction.DragRotate');
 
+goog.require('ol');
 goog.require('ol.ViewHint');
 goog.require('ol.events.ConditionType');
 goog.require('ol.events.condition');
@@ -68,7 +69,7 @@ ol.interaction.DragRotate.handleDragEvent_ = function(mapBrowserEvent) {
   var offset = mapBrowserEvent.pixel;
   var theta =
       Math.atan2(size[1] / 2 - offset[1], offset[0] - size[0] / 2);
-  if (this.lastAngle_ !== undefined) {
+  if (ol.isDef(this.lastAngle_)) {
     var delta = theta - this.lastAngle_;
     var view = map.getView();
     var rotation = view.getRotation();
diff --git a/src/ol/interaction/interaction.js b/src/ol/interaction/interaction.js
index a4e15be650..fc592ec716 100644
--- a/src/ol/interaction/interaction.js
+++ b/src/ol/interaction/interaction.js
@@ -3,6 +3,7 @@
 goog.provide('ol.interaction.Interaction');
 goog.provide('ol.interaction.InteractionProperty');
 
+goog.require('ol');
 goog.require('ol.MapBrowserEvent');
 goog.require('ol.Object');
 goog.require('ol.animation');
@@ -149,7 +150,7 @@ ol.interaction.Interaction.rotateWithoutConstraints =
   if (goog.isDefAndNotNull(rotation)) {
     var currentRotation = view.getRotation();
     var currentCenter = view.getCenter();
-    if (currentRotation !== undefined && currentCenter &&
+    if (ol.isDef(currentRotation) && currentCenter &&
         opt_duration && opt_duration > 0) {
       map.beforeRender(ol.animation.rotate({
         rotation: currentRotation,
@@ -220,10 +221,10 @@ ol.interaction.Interaction.zoomWithoutConstraints =
   if (goog.isDefAndNotNull(resolution)) {
     var currentResolution = view.getResolution();
     var currentCenter = view.getCenter();
-    if (currentResolution !== undefined && currentCenter &&
+    if (ol.isDef(currentResolution) && currentCenter &&
         opt_duration && opt_duration > 0) {
       map.beforeRender(ol.animation.zoom({
-        resolution: currentResolution,
+        resolution: /** @type {number} */ (currentResolution),
         duration: opt_duration,
         easing: ol.easing.easeOut
       }));
diff --git a/src/ol/interaction/interactiondefaults.js b/src/ol/interaction/interactiondefaults.js
index 081e22927c..2d40d36d26 100644
--- a/src/ol/interaction/interactiondefaults.js
+++ b/src/ol/interaction/interactiondefaults.js
@@ -1,5 +1,6 @@
 goog.provide('ol.interaction');
 
+goog.require('ol');
 goog.require('ol.Collection');
 goog.require('ol.Kinetic');
 goog.require('ol.interaction.DoubleClickZoom');
@@ -47,13 +48,13 @@ ol.interaction.defaults = function(opt_options) {
 
   var kinetic = new ol.Kinetic(-0.005, 0.05, 100);
 
-  var altShiftDragRotate = options.altShiftDragRotate !== undefined ?
+  var altShiftDragRotate = ol.isDef(options.altShiftDragRotate) ?
       options.altShiftDragRotate : true;
   if (altShiftDragRotate) {
     interactions.push(new ol.interaction.DragRotate());
   }
 
-  var doubleClickZoom = options.doubleClickZoom !== undefined ?
+  var doubleClickZoom = ol.isDef(options.doubleClickZoom) ?
       options.doubleClickZoom : true;
   if (doubleClickZoom) {
     interactions.push(new ol.interaction.DoubleClickZoom({
@@ -62,27 +63,27 @@ ol.interaction.defaults = function(opt_options) {
     }));
   }
 
-  var dragPan = options.dragPan !== undefined ? options.dragPan : true;
+  var dragPan = ol.isDef(options.dragPan) ? options.dragPan : true;
   if (dragPan) {
     interactions.push(new ol.interaction.DragPan({
       kinetic: kinetic
     }));
   }
 
-  var pinchRotate = options.pinchRotate !== undefined ? options.pinchRotate :
+  var pinchRotate = ol.isDef(options.pinchRotate) ? options.pinchRotate :
       true;
   if (pinchRotate) {
     interactions.push(new ol.interaction.PinchRotate());
   }
 
-  var pinchZoom = options.pinchZoom !== undefined ? options.pinchZoom : true;
+  var pinchZoom = ol.isDef(options.pinchZoom) ? options.pinchZoom : true;
   if (pinchZoom) {
     interactions.push(new ol.interaction.PinchZoom({
       duration: options.zoomDuration
     }));
   }
 
-  var keyboard = options.keyboard !== undefined ? options.keyboard : true;
+  var keyboard = ol.isDef(options.keyboard) ? options.keyboard : true;
   if (keyboard) {
     interactions.push(new ol.interaction.KeyboardPan());
     interactions.push(new ol.interaction.KeyboardZoom({
@@ -91,7 +92,7 @@ ol.interaction.defaults = function(opt_options) {
     }));
   }
 
-  var mouseWheelZoom = options.mouseWheelZoom !== undefined ?
+  var mouseWheelZoom = ol.isDef(options.mouseWheelZoom) ?
       options.mouseWheelZoom : true;
   if (mouseWheelZoom) {
     interactions.push(new ol.interaction.MouseWheelZoom({
@@ -99,7 +100,7 @@ ol.interaction.defaults = function(opt_options) {
     }));
   }
 
-  var shiftDragZoom = options.shiftDragZoom !== undefined ?
+  var shiftDragZoom = ol.isDef(options.shiftDragZoom) ?
       options.shiftDragZoom : true;
   if (shiftDragZoom) {
     interactions.push(new ol.interaction.DragZoom());
diff --git a/src/ol/interaction/modifyinteraction.js b/src/ol/interaction/modifyinteraction.js
index cb8989cd07..fa2a5040ff 100644
--- a/src/ol/interaction/modifyinteraction.js
+++ b/src/ol/interaction/modifyinteraction.js
@@ -7,6 +7,7 @@ goog.require('goog.events');
 goog.require('goog.events.Event');
 goog.require('goog.events.EventType');
 goog.require('goog.functions');
+goog.require('ol');
 goog.require('ol.Collection');
 goog.require('ol.CollectionEventType');
 goog.require('ol.Feature');
@@ -882,13 +883,13 @@ ol.interaction.Modify.prototype.removeVertex_ = function() {
       segmentsByFeature[uid] = [left, right, index];
     }
     newSegment = segmentsByFeature[uid];
-    if (left !== undefined) {
+    if (ol.isDef(left)) {
       newSegment[0] = left;
     }
-    if (right !== undefined) {
+    if (ol.isDef(right)) {
       newSegment[1] = right;
     }
-    if (newSegment[0] !== undefined && newSegment[1] !== undefined) {
+    if (ol.isDef(newSegment[0]) && ol.isDef(newSegment[1])) {
       component = coordinates;
       deleted = false;
       newIndex = index - 1;