swc-project/swc · error

Expected 'string' or 'ident' tokens

Error message

Expected 'string' or 'ident' tokens

What it means

Fired by the FamilyName parser: a font family name must be either a quoted string or a sequence of custom idents, but the current token is neither. The parser cannot build a FamilyName node from this token.

Source

Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:3337

                loop {
                    self.input.skip_ws();

                    if !is!(self, "ident") {
                        break;
                    }

                    value.push(self.parse()?);
                }

                Ok(FamilyName::SequenceOfCustomIdents(SequenceOfCustomIdents {
                    span: span!(self, span.lo),
                    value,
                }))
            }
            _ => {
                let span = self.input.cur_span();

                return Err(Error::new(
                    span,
                    ErrorKind::Expected("'string' or 'ident' tokens"),
                ));
            }
        }
    }
}

pub(crate) fn is_math_function(name: &Atom) -> bool {
    matches_eq_ignore_ascii_case!(
        name,
        "calc",
        "-moz-calc",
        "-webkit-calc",
        "sin",
        "cos",
        "tan",
        "asin",

View on GitHub (pinned to 5176682b65)

Solutions

1. Quote multi-word family names: font-family: "Helvetica Neue"
2. Use valid identifiers for unquoted names and avoid leading digits

When it happens

Trigger: Thrown at crates/swc_css_parser/src/parser/values_and_units/mod.rs:3337 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/ce4de2ba9d1bf9b4. Report an issue: GitHub.