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2619. Array Prototype Last

Description

Write code that enhances all arrays such that you can call theΒ array.last()Β method on any array and it will return the last element. If there are no elements in the array, it should returnΒ -1.

You may assume the array is the output ofΒ JSON.parse.

Β 

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.

Β 

Constraints:

  • arr is a valid JSON array
  • 0 <= arr.length <= 1000

Solutions

Solution 1

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declare global {
    interface Array<T> {
        last(): T | -1;
    }
}

Array.prototype.last = function () {
    return this.length ? this.at(-1) : -1;
};

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

export {};

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