{"record":{"id":"a6fa87e37ea15f9f","repo":"swc-project/swc","slug":"non-space-characters-found-without-seeing-a-doctyp","errorCode":null,"errorMessage":"Non-space characters found without seeing a doctype first, expected \"\"","messagePattern":"Non-space characters found without seeing a doctype first, expected \"\"","errorType":"exception","errorClass":"swc_html_parser::error::Error","httpStatus":null,"severity":"warning","filePath":"crates/swc_html_parser/src/parser/mod.rs","lineNumber":1426,"sourceCode":" // In any case, switch the insertion mode to \"before html\", then reprocess the\n // token.\n _ => {\n if !self.config.iframe_srcdoc {\n match &token {\n Token::StartTag { .. } => {\n self.errors.push(Error::new(\n token_and_info.span,\n ErrorKind::StartTagWithoutDoctype,\n ));\n }\n Token::EndTag { .. } => {\n self.errors.push(Error::new(\n token_and_info.span,\n ErrorKind::EndTagSeenWithoutDoctype,\n ));\n }\n Token::Character { .. } => {\n self.errors.push(Error::new(\n token_and_info.span,\n ErrorKind::NonSpaceCharacterWithoutDoctype,\n ));\n }\n Token::Eof => {\n self.errors.push(Error::new(\n token_and_info.span,\n ErrorKind::EofWithoutDoctype,\n ));\n }\n _ => {\n unreachable!();\n }\n }\n\n self.set_document_mode(DocumentMode::Quirks);\n }\n","sourceCodeStart":1408,"sourceCodeEnd":1444,"githubUrl":"https://github.com/swc-project/swc/blob/5176682b65416c6b5de6b47379ae1588ea3ecb3f/crates/swc_html_parser/src/parser/mod.rs#L1408-L1444","documentation":"Initial insertion mode, 'anything else' branch (crates/swc_html_parser/src/parser/mod.rs:1426): the first token is a character token that is not ASCII whitespace, no doctype preceded it, and iframe_srcdoc is false. Parse error; quirks mode is set and the character is reprocessed downstream. Leading whitespace is ignored by the initial mode and does NOT trigger this.","triggerScenarios":"Input whose first non-whitespace, non-comment content is text, e.g. `hello world` or `404: page not found` parsed as HTML with no doctype.","commonSituations":"Plain-text files fed to the HTML parser by content-sniffing code, error pages, template fragments starting with prose, log output wrapped in HTML parsing.","solutions":["Prepend `` and proper markup if the input is meant to be HTML","Check the content type before parsing — plain text should not go through the HTML parser","Set ParserConfig { iframe_srcdoc: true, .. } for fragment-like input"],"exampleFix":"// before\nlet fm = cm.new_source_file(file.into(), \"hello world, no markup\".into());\nlet doc = parse_file_as_document(&fm, config, &mut errors)?; // NonSpaceCharacterWithoutDoctype\n\n// after\nlet fm = cm.new_source_file(file.into(), \"hello world\".into());\nlet doc = parse_file_as_document(&fm, config, &mut errors)?;","handlingStrategy":"validation","validationCode":"fn starts_with_nonspace_text(html: &str) -> bool {\n let mut rest = html.trim_start();\n while let Some(t) = rest.strip_prefix(\"\") {\n Some(i) => rest = t[i + 3..].trim_start(),\n None => return false,\n }\n }\n let lower = rest.to_ascii_lowercase();\n !lower.is_empty() && !lower.starts_with(\"...` plus doctype when a Document is required","Set iframe_srcdoc = true for srcdoc parsing"],"tags":["html","parser","doctype","text-node","quirks-mode","swc"],"backgroundTag":"missing-doctype","analyzedSha":"5176682b65416c6b5de6b47379ae1588ea3ecb3f","analyzedAt":"2026-08-17T16:16:52.067Z","contentChangedAt":"2026-08-17T16:16:52.067Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}