Minimum Depth of Binary Tree LeetCode solution in JavaScript

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var minDepth = function (root) {
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  if (!root) {
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    return 0;
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  }
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  if (root.left && root.right) {
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    return Math.min(minDepth(root.left), minDepth(root.right)) + 1;
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  }
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  if (root.right) {
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    return minDepth(root.right) + 1;
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  }
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  if (root.left) {
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    return minDepth(root.left) + 1;
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  }
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  return 1;
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};