# javascript_sm URL: /api/lexers/javascript_sm/ Section: lexers -------------------------------------------------------------------------------- javascript_sm - Rosettes window.BENGAL_THEME_DEFAULTS = { appearance: 'light', palette: 'brown-bengal' }; window.Bengal = window.Bengal || {}; window.Bengal.enhanceBaseUrl = '/rosettes/assets/js/enhancements'; window.Bengal.watchDom = true; window.Bengal.debug = false; window.Bengal.enhanceUrls = { 'toc': '/rosettes/assets/js/enhancements/toc.632a9783.js', 'docs-nav': '/rosettes/assets/js/enhancements/docs-nav.57e4b129.js', 'tabs': '/rosettes/assets/js/enhancements/tabs.aac9e817.js', 'lightbox': '/rosettes/assets/js/enhancements/lightbox.1ca22aa1.js', 'interactive': '/rosettes/assets/js/enhancements/interactive.fc077855.js', 'mobile-nav': '/rosettes/assets/js/enhancements/mobile-nav.d991657f.js', 'action-bar': '/rosettes/assets/js/enhancements/action-bar.d62417f4.js', 'copy-link': '/rosettes/assets/js/enhancements/copy-link.7d9a5c29.js', 'data-table': '/rosettes/assets/js/enhancements/data-table.1f5bc1eb.js', 'lazy-loaders': '/rosettes/assets/js/enhancements/lazy-loaders.a5c38245.js', 'holo': '/rosettes/assets/js/enhancements/holo.ee13c841.js', 'link-previews': '/rosettes/assets/js/enhancements/link-previews.8d906535.js' }; (function () { try { var defaults = window.BENGAL_THEME_DEFAULTS || { appearance: 'system', palette: '' }; var defaultAppearance = defaults.appearance; if (defaultAppearance === 'system') { defaultAppearance = (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) ? 'dark' : 'light'; } var storedTheme = localStorage.getItem('bengal-theme'); var storedPalette = localStorage.getItem('bengal-palette'); var theme = storedTheme ? (storedTheme === 'system' ? defaultAppearance : storedTheme) : defaultAppearance; var palette = storedPalette ?? defaults.palette; document.documentElement.setAttribute('data-theme', theme); if (palette) { document.documentElement.setAttribute('data-palette', palette); } } catch (e) { document.documentElement.setAttribute('data-theme', 'light'); } })(); { "prerender": [ { "where": { "and": [ { "href_matches": "/docs/*" }, { "not": { "selector_matches": "[data-external], [target=_blank], .external" } } ] }, "eagerness": "conservative" } ], "prefetch": [ { "where": { "and": [ { "href_matches": "/*" }, { "not": { "selector_matches": "[data-external], [target=_blank], .external" } } ] }, "eagerness": "conservative" } ] } Skip to main content Magnifying Glass ESC Recent Clear Magnifying Glass No results for "" Start typing to search... ↑↓ Navigate ↵ Open ESC Close Powered by Lunr ⌾⌾⌾ DocumentationInfoAboutArrow ClockwiseGet StartedCodeHighlightingPaletteStylingStarburstExtendingFormattersNoteTutorialsBookmarkReferenceReleasesDevGitHubAPI Reference Magnifying Glass Search ⌘K Palette Appearance Chevron Down Mode Monitor System Sun Light Moon Dark Palette Snow Lynx Brown Bengal Silver Bengal Charcoal Bengal Blue Bengal List ⌾⌾⌾ Magnifying Glass Search X Close Documentation Caret Down Info About Arrow Clockwise Get Started Code Highlighting Palette Styling Starburst Extending Formatters Note Tutorials Bookmark Reference Releases Dev Caret Down GitHub API Reference Palette Appearance Chevron Down Mode Monitor System Sun Light Moon Dark Palette Snow Lynx Brown Bengal Silver Bengal Charcoal Bengal Blue Bengal Rosettes API Reference Caret Right Formatters html null terminal Caret Right Lexers _scanners _state_machine bash_sm c_sm clojure_sm cpp_sm css_sm csv_sm cuda_sm cue_sm dart_sm diff_sm dockerfile_sm elixir_sm gleam_sm go_sm graphql_sm groovy_sm haskell_sm hcl_sm html_sm ini_sm java_sm javascript_sm jinja_sm json_sm julia_sm kida_sm kotlin_sm lua_sm makefile_sm markdown_sm mojo_sm nginx_sm nim_sm perl_sm php_sm pkl_sm plaintext_sm powershell_sm protobuf_sm python_sm r_sm ruby_sm rust_sm scala_sm sql_sm stan_sm swift_sm toml_sm tree_sm triton_sm typescript_sm v_sm xml_sm yaml_sm zig_sm Caret Right Themes _mapping _palette _roles palettes _config _escape _formatter_registry _parallel _protocol _registry _types delegate rosettes Rosettes API ReferenceLexers ᗢ Caret Down Link Copy URL External Open LLM text Copy Copy LLM text Share with AI Ask Claude Ask ChatGPT Ask Gemini Ask Copilot Module lexers.javascript_sm Hand-written JavaScript lexer using composable scanner mixins. O(n) guaranteed, zero regex, thread-safe. Language Support: ECMAScript 2024 (ES15) syntax Template literals (backtick strings with ${} interpolation) BigInt literals (123n suffix) Optional chaining (?.) and nullish coalescing (??) async/await, generators, classes All standard operators including ** (exponentiation) Architecture: This lexer demonstrates the mixin composition pattern. Most scanning logic is inherited from reusable mixins: CStyleCommentsMixin: // and /* */ comments CStyleNumbersMixin: Hex, octal, binary, floats with exponents CStyleStringsMixin: Double/single quotes with escapes, backticks CStyleOperatorsMixin: Configurable multi-char operators Only language-specific parts are implemented in this class: Keyword classification Identifier handling ($ allowed) Language-specific token types Performance: ~45µs per 100-line file, benefiting from optimized mixin code. Thread-Safety: All lookup tables (_KEYWORDS, _BUILTINS, etc.) are frozen sets. Mixins use only local variables in scanning methods. See Also: rosettes.lexers._scanners: Mixin definitions and configuration rosettes.lexers.typescript_sm: TypeScript extends this pattern 1Class Classes JavaScriptStateMachineLexer 2 ▼ JavaScript/ECMAScript lexer using composable mixins. Supports ES2024 syntax with all modern featur… JavaScript/ECMAScript lexer using composable mixins. Supports ES2024 syntax with all modern features. Most scanning logic is inherited from C-style mixins; only JS-specific parts are here. Configuration: NUMBER_CONFIG: Enables BigInt suffix ('n') STRING_CONFIG: Enables template literals (backticks) OPERATOR_CONFIG: JS-specific operators (===, ??, ?., etc.) Token Classification: Declaration keywords: function, class, const, let, var Namespace keywords: import, export, from Constants: true, false, null, undefined, NaN, Infinity Builtins: Array, Promise, console, window, etc. Methods tokenize 2 Iterator[Token] ▼ Tokenize JavaScript source code. def tokenize(self, code: str, config: LexerConfig | None = None) -> Iterator[Token] Parameters Name Type Description code — config — Default: None Returns Iterator[Token] Internal Methods 1 ▼ _classify_word 1 TokenType ▼ Classify an identifier. def _classify_word(self, word: str) -> TokenType Parameters Name Type Description word — Returns TokenType ← Previous java_sm Next → jinja_sm List © 2026 Rosettes built in ᓚᘏᗢ { "linkPreviews": { "enabled": true, "hoverDelay": 200, "hideDelay": 150, "showSection": true, "showReadingTime": true, "showWordCount": true, "showDate": true, "showTags": true, "maxTags": 3, "includeSelectors": [".prose"], "excludeSelectors": ["nav", ".toc", ".breadcrumb", ".pagination", ".card", "[class*='-card']", ".tab-nav", "[class*='-widget']", ".child-items", ".content-tiles"], "allowedHosts": [], "allowedSchemes": ["https"], "hostFailureThreshold": 3 } } window.BENGAL_LAZY_ASSETS = { tabulator: '/rosettes/assets/js/tabulator.min.js', dataTable: '/rosettes/assets/js/data-table.js', mermaidToolbar: '/rosettes/assets/js/mermaid-toolbar.9de5abba.js', mermaidTheme: '/rosettes/assets/js/mermaid-theme.344822c5.js', graphMinimap: '/rosettes/assets/js/graph-minimap.ff04e939.js', graphContextual: '/rosettes/assets/js/graph-contextual.355458ba.js' }; window.BENGAL_ICONS = { close: '/rosettes/assets/icons/close.911d4fe1.svg', enlarge: '/rosettes/assets/icons/enlarge.652035e5.svg', copy: '/rosettes/assets/icons/copy.3d56e945.svg', 'download-svg': '/rosettes/assets/icons/download.04f07e1b.svg', 'download-png': '/rosettes/assets/icons/image.c34dfd40.svg', 'zoom-in': '/rosettes/assets/icons/zoom-in.237b4a83.svg', 'zoom-out': '/rosettes/assets/icons/zoom-out.38857c77.svg', reset: '/rosettes/assets/icons/reset.d26dba29.svg' }; Arrow Up -------------------------------------------------------------------------------- Metadata: - Word Count: 796 - Reading Time: 4 minutes