接受单词数组并返回句子的函数

我的结果中包含,但我不应该拥有它。我应该使用函数表达式语法。

let makeSentence = function(str) {
  return str.toString(" ");
};
let getWords = function(str) {
  return str.toString(' ');
};
console.log(makeSentence(["When", "I", "was", "your", "age", "television", "was", "called", "books"]));
// expect "When I was your age television was called books"
console.log(makeSentence(getWords('alpha bravo')));
// expect "alpha bravo"