Maximum Level Sum of a Binary Tree LeetCode solution in JavaScript

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var maxLevelSum = function (root) {
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  let res;
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  let maxSum = -Infinity;
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  let currLevel = 1;
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  const queue = [root];
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  while (queue.length) {
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    let levelSize = queue.length;
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    let levelSum = 0;
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    for (let i = 0; i < levelSize; i++) {
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      let curr = queue.shift();
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      levelSum += curr.val;
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      if (curr.left) queue.push(curr.left);
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      if (curr.right) queue.push(curr.right);
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    }
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    if (maxSum < levelSum) {
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      res = currLevel;
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      maxSum = levelSum;
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    }
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    currLevel++;
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  }
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  return res;
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};