LeetCode //2619. Array Prototype Last (Day 23 of LC JavaScript Challenge)

2619. Array Prototype Last

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.

 

Example 1:

Input: nums = [1,2,3]
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.

Constraints:

• 0 <= arr.length <= 1000
• 0 <= arr[i] <= 1000

From: LeetCode
Link: 2619. Array Prototype Last

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Solution:

Ideas：

This code adds a last function to the Array prototype which means all arrays will have this function. The function checks if the array has any elements (this.length > 0). If it does, it returns the last element (this[this.length - 1]). If it doesn’t, it returns -1.

Code:

Array.prototype.last = function() {
    return this.length > 0 ? this[this.length - 1] : -1;
};

/**
 * const arr = [1, 2, 3];
 * arr.last(); // 3
 */
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