TheAlgorithms/JavaScript · error · Error

Invalid units

Error message

Invalid units

What it means

Thrown by lengthConversion when fromUnit or toUnit is not a key in the internal meters dictionary. Supported keys are exactly: mm, cm, m, km, inch, ft, yd, mi. The check uses the 'in' operator, so both the source and target unit must match one of those literal strings.

Source

Thrown at Conversions/LengthConversion.js:26

 * @throws {Error} If the units are invalid or not found in the conversion dictionary.
 */

const lengthConversion = (length, fromUnit, toUnit) => {
  // Define a dictionary to map units to meters
  const meters = {
    mm: 0.001,
    cm: 0.01,
    m: 1,
    km: 1000,
    inch: 0.0254,
    ft: 0.3048,
    yd: 0.9144,
    mi: 1609.34
  }

  // Check if the units are in the dictionary, otherwise, throw an error
  if (!(fromUnit in meters) || !(toUnit in meters)) {
    throw new Error('Invalid units')
  }

  // Perform the conversion
  const metersFrom = length * meters[fromUnit]
  const convertedLength = metersFrom / meters[toUnit]

  return convertedLength
}

export { lengthConversion }

View on GitHub (pinned to 5c39e87a9a)

Solutions

1. Use only the documented keys: mm, cm, m, km, inch, ft, yd, mi.
2. Map your own unit strings to these keys before calling, e.g. { meter: 'm', meters: 'm', feet: 'ft' }.
3. Lowercase and trim the unit strings to avoid case/whitespace mismatches.

Example fix

// before
lengthConversion(1, 'meter', 'feet')
// after
lengthConversion(1, 'm', 'ft')

const UNITS = new Set(['mm', 'cm', 'm', 'km', 'inch', 'ft', 'yd', 'mi'])
if (!UNITS.has(fromUnit) || !UNITS.has(toUnit)) {
  throw new Error(`Unsupported unit. Allowed: ${[...UNITS].join(', ')}`)
}
lengthConversion(length, fromUnit, toUnit)

const SUPPORTED = new Set(['mm', 'cm', 'm', 'km', 'inch', 'ft', 'yd', 'mi'])
const isSupportedUnit = (u) => SUPPORTED.has(u)

try {
  lengthConversion(length, fromUnit, toUnit)
} catch (e) {
  if (/Invalid units/.test(e.message)) {
    // map common synonyms (meter->m, feet->ft) then retry
  }
  throw e
}

When it happens

Trigger: Calling lengthConversion(1, 'meter', 'feet') (full names unsupported), lengthConversion(1, 'in', 'cm') ('in' is not 'inch'), lengthConversion(1, 'KG', 'm'), or lengthConversion(1, 'miles', 'km'). Even 'inches' (plural) fails.

Common situations: Using full unit names instead of the short codes; pluralizing ('inches', 'feet'); using 'in' abbreviation for inch (the API wants 'inch'); passing uppercase; mismapping imperial vs metric keys.

Related errors

• Duplicate characters in character set are not allowed
• Not a valid character: ${digit}
• Argument is not a valid HEX code!
• Invalid hex string.
• Input is not a valid RGB color.

AI-assisted analysis of TheAlgorithms/JavaScript@5c39e87a9a (2026-08-13). Data as JSON: /api/errors/05c643b49ae09778. Report an issue: GitHub.