Number of Matching Subsequences LeetCode solution in JavaScript

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var numMatchingSubseq = function (s, words) {
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  let subsequence = false;
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  let count = 0;
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  let prevIdx, idx;
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  for (const word of words) {
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    prevIdx = -1;
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    idx = -1;
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    subsequence = true;
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    for (let i = 0; i < word.length; i++) {
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      idx = s.indexOf(word[i], idx + 1);
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      if (idx > prevIdx) {
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        prevIdx = idx;
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      } else {
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        subsequence = false;
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        break;
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      }
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    }
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    if (subsequence) count++;
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  }
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  return count;
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};