krypton-grapher/src/index.js

Krypton Grapher is a lightweight JavaScript library for encrypting and decrypting text with ease. It offers simple APIs for implementing text security in your applications, whether for personal projects or professional use. Designed with flexibility an

export class Cryptographer {
  #englishAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  #ukraineAlphabet = "АБВГҐДЕЄЖЗИІЇЙКЛМНОПРСТУФХЦЧШЩЬЮЯ";

  #getAlphabet(char) {
    if (this.#englishAlphabet.includes(char.toUpperCase())) {
      return this.#englishAlphabet;
    } else if (this.#ukraineAlphabet.includes(char.toUpperCase())) {
      return this.#ukraineAlphabet;
    }

    return null;
  }

  #processText(text, shift, isDecrypt) {
    if (isDecrypt) shift = -shift;
    let result = "";

    for (const char of text) {
      const alphabet = this.#getAlphabet(char);

      if (alphabet !== null) {
        const isLower = char === char.toLowerCase();
        let index =
          (alphabet.indexOf(char.toUpperCase()) + shift) % alphabet.length;

        if (index < 0) index += alphabet.length;

        const newChar = alphabet.charAt(index);
        result += isLower ? newChar.toLowerCase() : newChar;
      } else {
        result += char;
      }
    }

    return result;
  }

  encrypt(text, shift) {
    return this.#processText(text, shift, false);
  }

  decrypt(text, lang, shift) {
    if (shift !== undefined) {
      return this.#processText(text, shift, true);
    } else {
      const alphabet =
        lang === "en" ? this.#englishAlphabet : this.#ukraineAlphabet;

      if (!alphabet) throw new Error("Unsupported language!");

      let possibilities = [];
      for (let i = 0; i < alphabet.length; i++) {
        possibilities.push(this.#processText(text, i, true));
      }

      return possibilities;
    }
  }
}