JavaScript check if variable exists (is defined/initialized)

Question

Which method of checking if a variable has been initialized is better/correct? (Assuming the variable could hold anything (string, int, object, function, etc.))

Answer 1

if (typeof console != "undefined") {    
   ...
}

Or better

if ((typeof console == "object") && (typeof console.profile == "function")) {    
   console.profile(f.constructor);    
}

Works in all browsers