swc-project/swc · error

Expected string token

Error message

Expected string token

What it means

Fired while parsing a Str (CSS string): the current token was not a String token, so no quoted string value could be produced. This `if !is!(self, "string")` check is a validation guard; input at fault is a string-required context (e.g. font family, content value, @import href) receiving an unquoted identifier or other token.

Source

Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:2570

                Ok(Percentage { span, value })
            }
            _ => {
                unreachable!()
            }
        }
    }
}

impl<I> Parse<Str> for Parser<I>
where
    I: ParserInput,
{
    fn parse(&mut self) -> PResult<Str> {
        let span = self.input.cur_span();

        if !is!(self, "string") {
            return Err(Error::new(span, ErrorKind::Expected("string token")));
        }

        match bump!(self) {
            Token::String { value, raw } => Ok(Str {
                span,
                value,
                raw: Some(raw),
            }),
            _ => {
                unreachable!()
            }
        }
    }
}

impl<I> Parse<Url> for Parser<I>
where
    I: ParserInput,

View on GitHub (pinned to 5176682b65)

Solutions

1. Wrap the value in quotes ('...' or "...") to make it a string
2. Use an Ident parser if an unquoted identifier was intended

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:2570 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of swc-project/swc@5176682b65 (2026-08-17). Data as JSON: /api/errors/8bd21702e59efd89. Report an issue: GitHub.