Minimum Operations to Reduce X to Zero LeetCode solution in JavaScript

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var minOperations = function (nums, x) {
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  let len = nums.length,
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    best = 0;
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  for (let i = 1; i < len; i++) nums[i] += nums[i - 1];
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  let y = nums[len - 1] - x;
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  if (y < 0) return -1;
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  if (y === 0) return len;
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  for (let i = -1, j = (l = 0); i < len - best && l <= x; l = nums[++i]) {
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    while (nums[j] - l < y) j++;
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    if (nums[j] - l === y) best = Math.max(best, j - i);
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  }
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  return best > 0 ? len - best : -1;
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};