1const findLucky = function(arr) {
2 let lucky = [-1];
3 let numObj = {};
4 for (num of arr) {
5 numObj[num] ? numObj[num] += 1 : numObj[num] = 1;
6 }
7 let nums = Object.keys(numObj);
8 let frequencies = Object.values(numObj);
9 for (let num in nums) {
10 if (nums[num] == frequencies[num]) {
11 lucky.push(frequencies[num]);
12 }
13 }
14 if (lucky.length === 1) {
15 return lucky;
16 } else {
17 return Math.max(...lucky);
18 }
19};