Delete and Earn LeetCode solution in JavaScript

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var deleteAndEarn = function (nums) {
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  let maxNumber = 0;
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  const cache = {};
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  const points = {};
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  function maxPoints(num) {
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    if (num === 0) {
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      return 0;
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    }
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    if (num === 1) {
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      return points[1] || 0;
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    }
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    if (cache[num] !== undefined) {
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      return cache[num];
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    }
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    const gain = points[num] || 0;
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    return (cache[num] = Math.max(
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      maxPoints(num - 1),
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      maxPoints(num - 2) + gain
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    ));
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  }
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  for (let num of nums) {
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    points[num] = (points[num] || 0) + num;
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    maxNumber = Math.max(maxNumber, num);
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  }
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  return maxPoints(maxNumber);
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};