JavaScript Array length on sparse arrays

let arr = ["Audi", "BMW",, "Mercedes"];
console.log(arr);
//Result:
//(4) ['Audi', 'BMW', empty, 'Mercedes']

let arr2 = [,,,,"JavaScript"];
console.log(arr2);
//Result:
//(5) [empty × 4, 'JavaScript']

let arr3 = []
arr3[50] = "Python";
console.log(arr3);
//Result:
//(51) [empty × 50, 'Python']