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JS
JavaScript error

SyntaxError

The JavaScript exception "unparenthesized unary expression can't appear on the left-hand side of '\*\*'" occurs when a unary operator (one of typeof, void, delete, await, !, ~, +, -) is used on the left operand of the exponentiation operator without parentheses.

Reference entryJavaScriptFetched
This is a reference entry from MDN Web Docs. A full explanation with fixes has not been written yet.

The error messages

SyntaxError: Unary operator used immediately before exponentiation expression. Parenthesis must be used to disambiguate operator precedence (V8-based)
As listed by MDN Web Docs
SyntaxError: unparenthesized unary expression can't appear on the left-hand side of '**' (Firefox)
As listed by MDN Web Docs
SyntaxError: Unexpected token '**'. Ambiguous unary expression in the left hand side of the exponentiation expression; parentheses must be used to disambiguate the expression. (Safari)
As listed by MDN Web Docs

Details

Category
SyntaxError
Severity
error
Runtime
both

Related errors

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Source: MDN Web Docs. Data fetched 2026-09-25T01:48:37.274Z.