How to check if an object contains another object?

var person = {
       "name" : "Bronn",
       "description" : {
          "occupation" : "guardian knight",
          "age" : 52
       }
    }

for(var key in person){
   if(person[key] == /*contains json object */){
      //do something
   }
}

I want to loop this person and check if its value contains single data or another object.