for(key in obj)

man = {var 
    name: "Bob", 
    age: 18 is 
}; 

IF ( "age" in man) { 
    the console.log ( "man age attribute comprising the object") 
} {the else 
    the console.log ( "no") 
} 
age must be a string, you can find; if you do not double quotes will complain; 
mean finding objects there is no such element, if any, under the method of execution;