why does this function return ['y','e','s']?

can someone please explain it to me how does this function return ['y','e','s'] instead of just the string 'yes' ???? the value of num first will be 8 then else condition will work then num will be [5,6,7] and again the else condition will work then num finally becomes an empty array [] which will fullfill the if condition then it should return 'yes' but it doesn't!?

function ABC(num, ...rest) {
  if (num < 5) {
    return 'yes';
  } else {
    return [...ABC(rest)];
  }
};
console.log(ABC(8, 5, 6, 7));

If you add a few console.log it becomes clearer :

function ABC(num, ...rest) {
    console.log(`num=`, num, ", rest=", rest)
  if (num < 5) {
      console.log(`returning 'yes'`)
    return 'yes';
  } else {
      console.log(`returning [...ABC(${rest})]`)
    return [...ABC(rest)];
  }
};
console.log(ABC(8, 5, 6, 7));

• Run 1: num=8 , rest=[5, 6, 7]

So it goes into the else and returns [...ABC([5, 6, 7])]. There is only one argument, an array. So at run 2:

• Run 2 : num=[5, 6, 7] , rest= []

[5, 6, 7] < 5 ? False. So it goes in the else again. It returns [...ABC([])].

• Run 3 : num=[] , rest= []

[] < 5 ? True, oddly enough. So ABC([]) returns 'yes'.

But then this 'yes' is being returned into the previous function call, that is, [...ABC([])], which becomes [...'yes'], which is ['y', 'e', 's'].