Find All Lonely Numbers in the Array LeetCode solution in JavaScript

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var findLonely = function (nums) {
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  let countMap = new Map();
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  let result = [];
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  for (let num of nums) {
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    countMap.set(num, (countMap.get(num) || 0) + 1);
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  }
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  for (let num of nums) {
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    if (
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      !countMap.has(num - 1) &&
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      !countMap.has(num + 1) &&
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      countMap.get(num) === 1
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    ) {
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      result.push(num);
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    }
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  }
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  return result;
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};