Length of Longest Fibonacci Subsequence LeetCode solution in JavaScript

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var lenLongestFibSubseq = function (arr) {
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  let ans = 2;
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  const set = new Set(arr);
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  const len = arr.length;
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  for (let i = 0; i < len; i++) {
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    for (let j = i + 1; j < len; j++) {
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      let a = arr[i],
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        b = arr[j],
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        len = 2;
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      while (set.has(a + b)) {
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        len++;
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        let temp = a + b;
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        a = b;
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        b = temp;
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      }
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      ans = Math.max(len, ans);
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    }
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  }
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  return ans == 2 ? 0 : ans;
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};