Problem : Array Prototype Last | #2619 | LeetCode
Write code that enhances all arrays such that you can call the `array.last()` method on any array and it will return the last element. If there are no elements in the array, it should return `-1`.
You may assume the array is the output of `JSON.parse`.
Example 1:
Input: nums = [null, {}, 3]
Output: 3
Explanation: Calling nums.last() should return the last element: 3.
Example 2:
Input: nums = []
Output: -1
Explanation: Because there are no elements, return -1.
Solution:
Array.prototype.last = function () {
// Check if the array is empty (has zero length).
if (this.length === 0) {
return -1;
} else {
// Return the last element of the array.
return this[this.length - 1];
}
};
/**
* const arr = [1, 2, 3];
* arr.last(); // 3
*/
Explanation:
Let's break down the code step by step:
1. We define a `last` method on the `Array` prototype.
2. Inside the `last` method, we first check if the array's length is equal to `0`, indicating an empty array. If it's empty, we return `-1`.
3. If the array is not empty, we use `this.length - 1` to access the last element of the array and return it.
Now, you can call the `last` method on any array, and it will return the last element or `-1` if the array is empty, as demonstrated in the example usage.