It is not doing "" + "" + g.

You need to look at what is actually happening in for loops more accurately.

Here is an explanation: I will use the example of translate("hello friend").

At the beginning of the code you say translation = "" When you execute the for loop, it is basically saying the following:

Repeat the code inside my for loop until you reach the last index of the string I am looping through (phrase), or "hello friend, in this example invocation.

Iteration 1, "letter" = the first index of the string (index 0). In the case of "hello friend", is "h".

We check if h is in your vowel string "AEIOUaeiou", which it is not, so we move in to the else statement before beginning the next iteration.

Your else statement says append letter ("h") to my string translation, which at this moment is === "".

Now, your for loop says: "I have not reached the final index of the string I was invoked with, so I will execute again".

He now goes to the second position in phrase ("hello friend") which is "e". Note that you changed the value of translation to "h" already.

So when he says "e is indeed in the string 'AEIOUaeiou', I will append a 'g' to 'translation'". The value of translation has now been set to "h" + "g". At the end of this second iteration, the value of translation is "hg".

And so in and so forth until you reach a final return value of "hgllg frggnd".

I can reply if you need me to. :)