diff --git a/js/CameraContainer.js b/js/CameraContainer.js
index 5bb1600..b59cc8a 100644
--- a/js/CameraContainer.js
+++ b/js/CameraContainer.js
@@ -4,7 +4,7 @@ var CameraContainer = function () {
 }
 
 CameraContainer.prototype.mainCamera = function(id) {
-    if (id === undefined) {
+    if (typeof id === 'undefined') {
         return this.cameras[this.current_camera];
     }
     if (id >= cameras.length || id < 0) {
@@ -37,7 +37,7 @@ CameraContainer.prototype.get = function(i) {
 
 CameraContainer.prototype.getById = function(id) {
     for (var i in this.cameras) {
-        if (this.cameras[i].mesh !== undefined) {
+        if (typeof this.cameras[i].mesh !== 'undefined') {
             if (this.cameras[i].mesh.id == id) {
                 return i;
             }
diff --git a/js/Cube.js b/js/Cube.js
index 1f2a07f..4210ea4 100644
--- a/js/Cube.js
+++ b/js/Cube.js
@@ -15,8 +15,8 @@ var Cube = function(size, style) {
     // Super constructor call
     Displayable.call(this);
 
-    if (size  === undefined) size = 100;
-    if (style === undefined) style = {};
+    if (typeof size  === 'undefined') size = 100;
+    if (typeof style === 'undefined') style = {};
 
     this.geometry = new THREE.BoxGeometry(size, size, size);
     // this.geometry.computeVertexNormals();
@@ -33,7 +33,7 @@ Cube.prototype.constructor = Cube;
 var Plane = function(size1, size2, style) {
     Displayable.call(this);
 
-    if (style === undefined)  style = {};
+    if (typeof style === 'undefined')  style = {};
 
     this.geometry = new THREE.PlaneBufferGeometry(size1, size2);
     this.material = new THREE.MeshLambertMaterial(style);
diff --git a/js/FixedCamera.js b/js/FixedCamera.js
index 88c21d1..10710c5 100644
--- a/js/FixedCamera.js
+++ b/js/FixedCamera.js
@@ -5,7 +5,7 @@ var FixedCamera = function(arg1, arg2, arg3, arg4, position, target) {
     THREE.PerspectiveCamera.apply(this, arguments);
 
     // Set Position
-    if (position === undefined) {
+    if (typeof position === 'undefined') {
         this.position = new THREE.Vector3(0,0,5);
     } else {
         this.position.x = position.x;
@@ -14,7 +14,7 @@ var FixedCamera = function(arg1, arg2, arg3, arg4, position, target) {
     }
 
 
-    if (target === undefined)
+    if (typeof target === 'undefined')
         target = new THREE.Vector3(0,0,0);
 
     var direction = target.clone();
diff --git a/scene/js/main.js b/scene/js/main.js
index e0bace3..b5d4be8 100644
--- a/scene/js/main.js
+++ b/scene/js/main.js
@@ -197,7 +197,7 @@ function click(event) {
 
             // Looking for cameras
             for (i in intersects) {
-                if (minDistance === undefined || intersects[i].distance < minDistance) {
+                if (typeof minDistance === 'undefined' || intersects[i].distance < minDistance) {
                     // We will not consider a line as clickable
                     if (! (intersects[i].object instanceof THREE.Line)) {
                         minDistance = intersects[i].distance;
@@ -205,7 +205,7 @@ function click(event) {
                     }
                 }
             }
-            if (bestIndex !== undefined) {
+            if (typeof bestIndex !== 'undefined') {
                 cameras.setById(intersects[bestIndex].object.id);
             }