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JavaScript private field syntax was used outside a class body

SyntaxError: Unexpected '#' used outside of class body

JavaScript encountered private field syntax in a location where class private names are not allowed.

SyntaxError: Unexpected '#' used outside of class bodyclasses

Observed message

SyntaxError: Unexpected '#' used outside of class body

Why it happens

  • A private field name is used outside a class body.
  • Code tries to access or declare #private syntax in plain objects or functions.
  • Transformed or copied class code lost the surrounding class context.

How to fix it

  1. Use #private names only inside classes that declare them.
  2. Do not reference private fields from plain objects or unrelated scopes.
  3. Check transpilation or copied snippets if the class wrapper is missing.

Official reference

MDN: SyntaxError: Unexpected # used outside of class body

Related errors

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