JavaScript Array length property dense array add and remove

let arr = ["Audi", "BMW", "Mercedes"];
/**
 * We know that arr.length === 3
 * Let's add an element to array
 * */
arr.push("Ferrari");

let length = arr.length;

console.log(arr.length);
// Result:
// 4

/**
 * In previous example highest index
 * was 2, let's check it now, after
 * we have added another element
 * */

console.log(arr.length-1);
// Result:
//3

//Let's empty our array
arr = [];
console.log(arr.length);
// Result:
// 0