for loop inside a for loop javascript

function multiplyAll(arr) {
  var product = 1;
  // Only change code below this line
  for (var i=0; i<arr.length; i++ ){
    for (var j=0; j<arr[i].length; j++){
      product*=arr[j];
     
    }
  }
  // Only change code above this line
  return product;
}

// Modify values below to test your code
multiplyAll([[1,2],[3,4],[5,6,7]]);