tailwindlabs/tailwindcss · error · TypeError

`CSS.escape` requires an argument.

Error message

`CSS.escape` requires an argument.

What it means

Thrown by escape() in escape.ts to mirror the native CSS.escape() Web API, which requires exactly one argument. The check uses arguments.length === 0 so it fires only when the function is called with no arguments at all — not when undefined is passed (undefined gets coerced to the string 'undefined'). It is a TypeError, not a generic Error, matching the spec.

Source

Thrown at packages/tailwindcss/src/utils/escape.ts:4

// https://drafts.csswg.org/cssom/#serialize-an-identifier
export function escape(value: string) {
  if (arguments.length === 0) {
    throw new TypeError('`CSS.escape` requires an argument.')
  }
  let string = String(value)
  let length = string.length
  let index = -1
  let codeUnit: number
  let result = ''
  let firstCodeUnit = string.charCodeAt(0)

  if (
    // If the character is the first character and is a `-` (U+002D), and
    // there is no second character, […]
    length === 1 &&
    firstCodeUnit === 0x002d
  ) {
    return '\\' + string
  }

  while (++index < length) {

View on GitHub (pinned to 16e94cbf7f)

Solutions

1. Pass the identifier string: escape('my-class').
2. If the value may be absent, guard the call: value !== undefined && escape(value).
3. Prefer TypeScript to catch missing-argument calls at compile time (the signature is escape(value: string)).

Example fix

// before — throws at runtime
let id = escape()

// after
let id = escape('my-class')

if (arguments.length === 0 || value === undefined) {
  throw new TypeError('escape requires a value')
}
escape(value)

function isEscapable(value: unknown): value is string {
  return typeof value === 'string'
}

When it happens

Trigger: Calling escape() with no arguments: escape(). Calling it via apply/call with an empty array. Destructuring or spreading that accidentally drops the argument.

Common situations: Refactoring a call site and dropping the argument. Using .map(escape) on an array that contains holes or is unexpectedly empty in a way that bypasses the argument (note: .map(escape) actually passes the element, so this is safe; the real trigger is a bare escape()).

Related errors

• Invalid theme value `${value}` for namespace `${key}`
• The pattern `${pattern}` is not balanced.
• Step cannot be zero in sequence expansion.
• Cannot use `@variant` with empty variant
• Cannot use `@variant` with unknown variant: ${variant}

AI-assisted analysis of tailwindlabs/tailwindcss@16e94cbf7f (2026-08-12). Data as JSON: /api/errors/6eb6ff33e3c0b09a. Report an issue: GitHub.