如何查找应用程序是在facebook内还是在facebook外运行

Question

How can we find using PHP or Javascript if the facebook app is running within Facebook or running outside of Facebook as a Website. Am not sure what should be the criterion to check?

Answer 1

Did some checking. The answer below works:

if(isset($_REQUEST["signed_request"]){
// Opened in facebook
}else{

//opened outside facebook.
}