recursion in array to find odd numbers and push to new variable

Question

I tried to recursion those arrays to find odd/even numbers then push them to newArr but the result, not an array, that result is the string with numbers the result after found the odd/even numbers.

this is the code i wrote,

function odd(nums){
  var result = [];
  if(nums.length === 0) {
    return result;
  } else  if (nums[0] % 2 === 0){
    result.push(nums[0])
    // return odd(nums.slice(1))
  };
  return result + odd(nums.slice(1));
};

var arr = [1,8,3,4,4,5,9,13,13,9,10];
var print = odd(arr);
console.log(print)

if i don't write return result + odd(nums.slice(1)); the result nothing / undefined,

can anyone help me to explain why that result in a string, not an array I wanted

Answer 1

You need to concat arrays. + does only work for strings or for numbers.

BTW, after block statements { ... }, you do not need a semicolon.

function odd(nums){
    var result = [];
    if (nums.length === 0) {
        return result;
    } 
    if (nums[0] % 2 === 0) {
        result.push(nums[0]);
    }
    return result.concat(odd(nums.slice(1)));
}

var arr = [1, 8, 3, 4, 4, 5, 9, 13, 13, 9, 10];
var print = odd(arr);
console.log(print);