Building Boxes LeetCode solution in JavaScript

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var minimumBoxes = function (n) {
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  //Binary search for the height of the biggest triangle I can create with n cubes available.
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  let lo = 1,
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    hi = n,
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    result;
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  let totalCubes = (x) => (x * (x + 1) * (x + 2)) / 6; //the total cubes of a triangle with height x
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  while (lo + 1 < hi) {
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    let mid = (lo + hi) >> 1;
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    if (totalCubes(mid) <= n) lo = mid;
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    else hi = mid;
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  }
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  let f = (x) => Math.floor(Math.sqrt(2 * x) + 1 / 2); // the i-th element of the sequence 1,2,2,3,3,3,4,4,4,4,5,...
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  result = (lo * (lo + 1)) / 2; // the base of the largest complete triangle 1+2+3+..+H
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  n -= totalCubes(lo); //remove the cubes of the complete triangle
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  return result + f(n); // the base of the largest+ the extra floor cubes
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};