Undefined value in last iteration to traverse nested array

Question

I made the following code with the intention of traversing the following array:

[[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]

Everything is happening as I wanted, all array values are being displayed but the last console.log returns undefined, I don’t know why. The following code:

let vet = [[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]];

function showNums(arr) {
    for(let i = 0; i < arr.length; i++){
      for(let j = 0; j < arr[i].length; j++){
        console.log(arr[i][j]);
      }
    }
}
  
console.log(showNums(vet));

Answer 1

Its function does not return any value (it has none return within it). And in such cases, the "return" of it is undefined. Ex

function comReturn() {
    console.log('eu retorno um valor');
    return 1;
}
function semReturn() {
    console.log('eu não retorno nada');
}

let x = comReturn();
let y = semReturn();

console.log(x); // 1
console.log(y); // undefined

That is, the function showNums returns undefined, and how you had her return printed, the undefined is printed at the end.

Therefore, simply call the function, without printing the return:

let vet = [[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]];

function showNums(arr) {
    for(let i = 0; i < arr.length; i++){
      for(let j = 0; j < arr[i].length; j++){
        console.log(arr[i][j]);
      }
    }
}

showNums(vet);