Maximize Number of Subsequences in a String LeetCode solution in JavaScript

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/**
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 * @param {string} text
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 * @param {string} pattern
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 * @return {number}
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 */
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var maximumSubsequenceCount = function (text, pattern) {
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  const arrText = text.split("");
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  const lengthP0 = arrText.filter((x) => x === pattern[0]).length;
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  const lengthP1 = arrText.filter((x) => x === pattern[1]).length;
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  const [c1, c2, lengthmax] =
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    lengthP0 <= lengthP1
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      ? [...pattern, lengthP1]
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      : [pattern[1], pattern[0], lengthP0];
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  let newText = lengthP0 <= lengthP1 ? [c1, ...arrText] : [...arrText, c1];
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  newText = lengthP0 <= lengthP1 ? newText : newText.reverse();
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  let i = 0;
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  let count = 0;
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  let countmax = lengthmax;
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  while (i < newText.length) {
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    if (newText[i] === c1) {
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      count += countmax;
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    }
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    if (newText[i] === c2) {
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      countmax--;
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    }
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    i++;
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  }
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  return count;
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};