Find Pivot Index LeetCode solution in JavaScript

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/**
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 * @param {number[]} nums
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 * @return {number}
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 */
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var pivotIndex = function (nums) {
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  //step 1
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  var tot = 0;
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  for (let i = 0; i < nums.length; i++) {
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    tot += nums[i];
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  }
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  // Step 2
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  left = 0;
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  for (let j = 0; j < nums.length; j++) {
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    right = tot - nums[j] - left;
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    if (left == right) {
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      return j;
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    }
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    left += nums[j];
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  }
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  return -1;
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};