JSON crawler function returning undefined

I have a recursive JSON crawler function that looks for a specified function then returns it. However, it is returning undefined and I am not sure why.

Here is the script:

function get(what, where){
    where = typeof(where) != 'undefined' ? where : user.object;
    for(entry in where){
        if(typeof(where[entry]) =="string开发者_运维知识库"){
            if (entry == what) {
                result = where[entry];
                console.log(result)
                return result;
            }
        }else if(typeof(where[entry]) =="object"){   
            get(what, where[entry]);
        }
    }
}

the console.log returns correctly but the return statement below it fails.

---

It's because you're not returning your recursive branch of the code, this:

get(what, where[entry]);

should be:

return get(what, where[entry]);

So on that branch, though you're executing all the way down, you're not returning the result back up, so you get the default return: undefined.

---

If you dont write a return-statement in a JavaScript function, but it reaches its end anyway, then it returns undefined. That is (probably) what has happened here, since if you dont enter the if-statement with the return-statement, you will not get to return anything.

EDIT:

As a rule of thumb, you should ALWAYS return something in every bransch of your code. A static language compiler would have warned you about this, but here you have to make sure yourself.

Example:

function get(what, where){
    where = typeof(where) != 'undefined' ? where : user.object;
    for(entry in where){
        if(typeof(where[entry]) =="string"){
            if (entry == what) {
                result = where[entry];
                console.log(result)
                return result;
            }
        }else if(typeof(where[entry]) =="object"){   
            get(what, where[entry]);
            // Are you sure you don't want to return anything here?.. hm...
        }
    }
    // Here be dragons! What will be returned from the function?
    // Hint: Undefined! :)
}

Both those places could probably use return statements. The last one need one because what if the for-loop doesn't have any entries to enumerate over?

---

You probably want to modify the code:

get(what, where[entry]);

to

return get(what, where[entry]);

:-P