Find and Replace Pattern LeetCode solution in JavaScript

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var findAndReplacePattern = function (words, pattern) {
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  let ans = [],
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    codex = new Map();
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  const translate = (char) => {
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    if (!codex.has(char)) codex.set(char, String.fromCharCode(97 + codex.size));
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    return codex.get(char);
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  };
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  const compare = (word) => {
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    codex.clear();
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    for (let i = 0; i < word.length; i++)
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      if (translate(word[i]) !== cipher[i]) return;
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    ans.push(word);
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  };
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  let cipher = new Array(pattern.length);
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  for (let i = 0; i < pattern.length; i++)
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    cipher[i] = translate(pattern.charAt(i));
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  words.forEach(compare);
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  return ans;
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};