TheAlgorithms/JavaScript · error · TypeError

Arguments type are invalid

Error message

Arguments type are invalid

What it means

XORCipher rejects the call when str is not a string OR key is not an integer. It XORs each character's charCodeAt with the key bitwise, which only makes sense for a string input and a whole-number key; a float key or non-string str would yield undefined/garbled output.

Source

Thrown at Ciphers/XORCipher.js:14

/**
 * @function XORCipher
 * @description - Encrypt using an XOR cipher
 * The XOR cipher is a type of additive cipher.
 * Each character is bitwise XORed with the key.
 * We loop through the input string, XORing each
 * character with the key.
 * @param {string} str - string to be encrypted
 * @param {number} key - key for encryption
 * @return {string} encrypted string
 */
const XORCipher = (str, key) => {
  if (typeof str !== 'string' || !Number.isInteger(key)) {
    throw new TypeError('Arguments type are invalid')
  }

  return str.replace(/./g, (char) =>
    String.fromCharCode(char.charCodeAt() ^ key)
  )
}

export default XORCipher

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Pass a string and an integer key: XORCipher('msg', 42).
2. Parse the key: Math.trunc(Number(rawKey)).
3. Decode str buffers to utf8 first.

Example fix

// before
XORCipher(buffer, process.env.XOR_KEY) // Buffer + string
// after
XORCipher(buffer.toString('utf8'), Math.trunc(Number(process.env.XOR_KEY)))

function xorSafe(text, rawKey) {
  const key = Math.trunc(Number(rawKey));
  return XORCipher(String(text), key);
}

/** @param {unknown} s @param {unknown} k @returns {boolean} */
const validXorArgs = (s, k) => typeof s === 'string' && Number.isInteger(k);

try { return XORCipher(text, key); }
catch (e) {
  if (e instanceof TypeError && /Arguments type are invalid/.test(e.message)) {
    return XORCipher(String(text), Math.trunc(Number(key)));
  }
  throw e;
}

When it happens

Trigger: str is a number/object/Buffer, or key is a float (e.g. 3.5), a string ("7"), NaN, undefined, or any non-integer.

Common situations: Key read from a config/env as a string, str passed as a Buffer from file/crypto input, or a computed key that ended up fractional.

Related errors

• Argument not an Integer
• Rule must be an integer between the values 0 and 255 (got ${
• Coefficient a, b should be number
• Argument str should be String
• Argument should be string

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/6df46bb38b50777f. Report an issue: GitHub.