Numbers At Most N Given Digit Set LeetCode solution in JavaScript

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var atMostNGivenDigitSet = function (digits, n) {
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  const asString = "" + n;
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  let smaller = 0;
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  let prev = 1;
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  for (let i = asString.length - 1; i >= 0; --i) {
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    const L = asString.length - 1 - i;
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    const num = +asString[i];
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    let equal = 0;
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    let less = 0;
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    for (let digit of digits) {
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      if (digit == num) {
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        equal = 1;
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      }
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      if (digit > num) {
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        break;
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      }
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      if (digit < num) {
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        less++;
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      }
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    }
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    prev = less * Math.pow(digits.length, L) + equal * prev;
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    if (L < asString.length - 1) {
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      smaller += Math.pow(digits.length, L + 1);
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    }
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  }
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  return smaller + prev;
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};