Next Permutation LeetCode solution in JavaScript

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/**
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 * @param {number[]} nums
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 * @return {void} Do not return anything, modify nums in-place instead.
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 */
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var nextPermutation = function (nums) {
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  const dsc = nums.slice();
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  dsc.sort((a, b) => b - a);
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  if (dsc.every((n, i) => n === nums[i])) {
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    nums.sort((a, b) => a - b);
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  } else {
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    const len = nums.length;
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    let lo = len - 1,
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      hi;
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    while (nums[lo] === dsc[dsc.length - 1]) {
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      lo--;
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      dsc.pop();
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    }
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    while (lo >= 0) {
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      // console.log(lo, nums[lo], nums.slice(lo + 1))
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      hi = nums
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        .slice(lo + 1)
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        .reverse()
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        .findIndex((n) => n > nums[lo]);
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      if (hi !== -1) {
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        hi = len - 1 - hi;
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        break;
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      }
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      lo--;
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    }
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    const lval = nums[lo];
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    // console.log(lo, lval, hi, nums[hi]);
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    nums[lo] = nums[hi];
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    nums[hi] = lval;
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    const sorted = nums.slice(lo + 1);
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    // console.log(nums, sorted)
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    sorted.sort((a, b) => a - b);
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    for (let i = 0; i < sorted.length; i++) nums[lo + 1 + i] = sorted[i];
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  }
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};