Array Nesting LeetCode solution in JavaScript

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var arrayNesting = function (nums) {
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  return nums.reduce((result, num, index) => {
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    let count = 1;
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    while (nums[index] !== index) {
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      const next = nums[index];
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      [nums[index], nums[next]] = [nums[next], nums[index]];
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      count += 1;
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    }
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    return Math.max(result, count);
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  }, 0);
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};