Number of Valid Words for Each Puzzle LeetCode solution in JavaScript

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var findNumOfValidWords = function (words, puzzles) {
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  // Form map of word's bitmasks
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  const wordsMaskMap = words.reduce(
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    (map, word) => addToMap(map, getMask(word)),
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    new Map()
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  );
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  return puzzles.map((puzzle) => {
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    const pMask = getMask(puzzle);
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    const pFirstMask = getFirstMask(puzzle);
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    let count = 0;
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    // Verify each bitmask against a given puzzle
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    for (let wMask of wordsMaskMap.keys()) {
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      if (wMask & pFirstMask && !((wMask | pMask) ^ pMask)) {
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        count += wordsMaskMap.get(wMask);
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      }
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    }
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    return count;
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  });
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};
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// Transform a char into a bit index
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var getBit = (char) => 1 << (char.charCodeAt(0) - "a".charCodeAt(0));
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// Transform a word into a bitmask
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var getMask = (word) => word.split("").reduce((acc, c) => acc | getBit(c), 0);
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// Get a bitmask for the first letter of a word
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var getFirstMask = (word) => getBit(word[0]);
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// Helper function to count hashes in a Map object
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var addToMap = (map, val) =>
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  map.has(val) ? map.set(val, map.get(val) + 1) : map.set(val, 1);