TheAlgorithms/JavaScript · error · TypeError

Argument is not a string.

Error message

Argument is not a string.

What it means

Thrown as a TypeError by CheckKebabCase() when varName is not a string. The function tests varName against a regex and calls varName.includes('_'), both requiring a string. Kebab-case means lowercase words joined by hyphens (e.g. 'my-var-name').

Source

Thrown at String/CheckKebabCase.js:13

// CheckKebabCase method checks the given string is in kebab-case or not.

// Problem Source & Explanation: https://en.wikipedia.org/wiki/Naming_convention_(programming)

/**
 * CheckKebabCase method returns true if the string in kebab-case, else return the false.
 * @param {String} varName the name of the variable to check.
 * @returns `Boolean` return true if the string is in kebab-case, else return false.
 */
const CheckKebabCase = (varName) => {
  // firstly, check that input is a string or not.
  if (typeof varName !== 'string') {
    throw new TypeError('Argument is not a string.')
  }

  const pat = /(\w+)-(\w)([\w-]*)/
  return pat.test(varName) && !varName.includes('_')
}

export { CheckKebabCase }

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Coerce: CheckKebabCase(String(name)).
2. Type-guard before calling.
3. Ensure the upstream always produces strings.

Example fix

// before
CheckKebabCase(key)

// after
CheckKebabCase(String(key ?? ''))

function safeCheckKebabCase(name) {
  if (typeof name !== 'string') {
    throw new TypeError('Expected a string')
  }
  return CheckKebabCase(name)
}

function isString(v) {
  return typeof v === 'string'
}

try {
  CheckKebabCase(name)
} catch (e) {
  if (e instanceof TypeError && e.message === 'Argument is not a string.') {
    return false
  }
  throw e
}

When it happens

Trigger: Calling CheckKebabCase(null), CheckKebabCase(undefined), CheckKebabCase(123), or CheckKebabCase(['my-var']).

Common situations: Config key validation where keys can be numbers; missing fields in parsed YAML/JSON; values from a generic map typed as unknown.

Related errors

• Argument is not a string.
• Argument is not a string.
• Invalid Input
• Argument should be string
• Both arguments should be strings.

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/7897410086bfb9ac. Report an issue: GitHub.