let myFriends = ["John", "Jane", "Irma", "Anna"];

// -- My friends are ${friend}.

function createSentence(friends) {
    let friendsStr = "";
    for (let i = 0; i < friends.length; i++) {
        if (i === 0) {
        friendsStr += friends[i];
        } else if (i === friends.length-1) {
            friendsStr += ", and " + friends[i];
        }
        else {
        friendsStr += ", " + friends[i];
        }
    }
    let sentence = `My friends are ${friendsStr}!`;
    return sentence;
}
console.log(createSentence(myFriends));