Why Array(1).join('str') output empty?

Question

Why below block of code not output string ?

I was expecting it should display abc when we pass num=1.

What I am missing here ?

function repeatStringNumTimes(str, num) {
  return Array(num).join(str);
}
console.log(repeatStringNumTimes("abc", 1));

Answer 1

You need at least two elements for Array#join with a separator, because one element is just converted to a string and it does not need any glue.

function repeatStringNumTimes(str, num) {
    return Array(num + 1).join(str);
}
console.log(repeatStringNumTimes("abc", 1));