Non-negative Integers without Consecutive Ones LeetCode solution in JavaScript

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var findIntegers = function (n) {
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  let dp = (len) => {
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    if (len < 0) return 0;
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    if (!len) return 1;
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    let _0x = 1; // number of accepted combination when '1' is first
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    let _1x = 1; // number of accepted combination when '0' is first
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    while (--len) [_0x, _1x] = [_0x + _1x, _0x];
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    return _0x + _1x;
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  };
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  let binary = n.toString(2);
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  let count = 0;
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  let is_prev_one = false;
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  for (let i = 0; i < binary.length; i++) {
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    if (binary[i] === "0") {
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      is_prev_one = false;
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      continue;
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    }
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    count += dp(binary.length - i - 1);
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    if (is_prev_one) return count;
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    is_prev_one = true;
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  }
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  return count + 1;
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};