Encrypt and Decrypt Strings LeetCode solution in JavaScript

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var Encrypter = function (keys, values, dictionary) {
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  this.encryptMap = new Map();
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  for (let i = 0; i < keys.length; i++) {
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    this.encryptMap.set(keys[i], values[i]);
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  }
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  this.dict = new Set(dictionary);
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  // Encypt the values in dict for easy comparison later
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  this.encryptedVals = [];
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  for (let word of this.dict) {
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    this.encryptedVals.push(this.encrypt(word));
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  }
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};
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Encrypter.prototype.encrypt = function (word1) {
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  let encrypted = "";
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  for (let char of word1) {
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    encrypted += this.encryptMap.get(char);
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  }
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  return encrypted;
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};
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Encrypter.prototype.decrypt = function (word2) {
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  return this.encryptedVals.filter((x) => x === word2).length;
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};