Fixed #4

LICENSE

@@ -0,0 +1,20 @@
+The MIT License (MIT)
+
+Copyright (c) 2017 [Muaz Khan](https://github.com/muaz-khan)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

getScreenId.js

@@ -1,4 +1,4 @@
-// Last time updated at Feb 16, 2017, 08:32:23
+// Last time updated on Oct 26, 2017
 
 // Latest file can be found here: https://cdn.webrtc-experiment.com/getScreenId.js
 
@@ -44,15 +44,20 @@ getScreenId(function (error, sourceId, screen_constraints) {
             if (event.data.chromeMediaSourceId) {
                 if (event.data.chromeMediaSourceId === 'PermissionDeniedError') {
                     callback('permission-denied');
-                } else callback(null, event.data.chromeMediaSourceId, getScreenConstraints(null, event.data.chromeMediaSourceId));
+                } else {
+                    callback(null, event.data.chromeMediaSourceId, getScreenConstraints(null, event.data.chromeMediaSourceId));
+                }
+
+                // this event listener is no more needed
+                window.removeEventListener('message', onIFrameCallback);
             }
 
             if (event.data.chromeExtensionStatus) {
                 callback(event.data.chromeExtensionStatus, null, getScreenConstraints(event.data.chromeExtensionStatus));
-            }
 
-            // this event listener is no more needed
-            window.removeEventListener('message', onIFrameCallback);
+                // this event listener is no more needed
+                window.removeEventListener('message', onIFrameCallback);
+            }
         }
 
         setTimeout(postGetSourceIdMessage, 100);
@@ -136,10 +141,10 @@ getScreenId(function (error, sourceId, screen_constraints) {
 
             if (event.data.chromeExtensionStatus) {
                 callback(event.data.chromeExtensionStatus);
-            }
 
-            // this event listener is no more needed
-            window.removeEventListener('message', onIFrameCallback);
+                // this event listener is no more needed
+                window.removeEventListener('message', onIFrameCallback);
+            }
         }
 
         setTimeout(postGetChromeExtensionStatusMessage, 100);

index.html

@@ -272,7 +272,7 @@ <h2 class="header specific-h2">Prerequisites</h2>
                     </li>
 
                     <li>
-                        Firefox? <a href="https://addons.mozilla.org/en-US/firefox/addon/enable-screen-capturing/" target="_blank">Store</a> / <a href="https://github.com/muaz-khan/Firefox-Extensions/tree/master/enable-screen-capturing">Source Code</a>
+                        Firefox? Requires version 52 or higher; and HTTPs.
                     </li>
                 </ol>
             </section>