N-Repeated Element in Size 2N Array.js

/*
In a array A of size 2N, there are N+1 unique elements, and exactly one of these elements is repeated N times.

Return the element repeated N times.

Example 1:
Input: [1,2,3,3]
Output: 3

Example 2:
Input: [2,1,2,5,3,2]
Output: 2

Example 3:
Input: [5,1,5,2,5,3,5,4]
Output: 5

*/
/**
 * @param {number[]} A
 * @return {number}
 */
var repeatedNTimes = function(arr) {
    let map = {};
    
    for (let i = 0; i < arr.length; i++) {
        if (map[arr[i]]) return arr[i];
        map[arr[i]] = true;
    }
};