# yuku-parser > A fast, spec-compliant JavaScript and TypeScript parser, producing an ESTree / TypeScript-ESTree AST Latest version **0.17.0** (published 2026-10-02) · MIT license · 0 weekly downloads ## Install ```sh npm install yuku-parser pnpm add yuku-parser yarn add yuku-parser bun add yuku-parser ``` ## Health **Score 70/100 (B)** — status: active. Positive: has types; esm support; no vulnerabilities; has provenance; recently updated; high maintenance score. Warnings: low downloads; pre 1.0. ## Facts | | | |---|---| | Version | 0.17.0 | | Published | 2026-10-02 | | First published | 2026-02-28 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | ESM + CommonJS | | Node | >=14.18.0 | | Dependencies | 2 | | Unpacked size | 46.6 KB | | Known vulnerabilities | 0 | | Install scripts | no | | Provenance | attested (GitHub Actions) | | GitHub stars | 942 | | Maintainers | arshadyaseen | | Keywords | acorn, ast, babel, compiler, ecmascript, espree, fast, javascript, js, jsx, lexer, oxc, parser, rust, swc, tokenizer, ts, tsx, typescript | ## Links - npm: https://www.npmjs.com/package/yuku-parser - Repository: https://github.com/yuku-toolchain/yuku - Homepage: https://github.com/yuku-toolchain/yuku#readme - Issues: https://github.com/yuku-toolchain/yuku/issues - npm.io page: https://npm.io/package/yuku-parser ## Dependencies (2) - [yuku-core](https://npm.io/package/yuku-core.md) 0.17.0 - [@yuku-toolchain/types](https://npm.io/package/@yuku-toolchain/types.md) ^0.17.0 ## Alternatives - [@mapbox/jsonlint-lines-primitives](https://npm.io/package/@mapbox/jsonlint-lines-primitives.md) — 5.3M weekly downloads - [reftools](https://npm.io/package/reftools.md) — 3.5M weekly downloads - [@hey-api/openapi-ts](https://npm.io/package/@hey-api/openapi-ts.md) — 3.5M weekly downloads - [@mapbox/geojson-rewind](https://npm.io/package/@mapbox/geojson-rewind.md) — 2.4M weekly downloads - [turbo-stream](https://npm.io/package/turbo-stream.md) — 1.7M weekly downloads ## Recent versions - 0.17.0 (latest) — 2026-10-02 - 0.5.0-beta.2 (beta) — 2026-05-04 - 0.15.1 — 2026-10-02 - 0.15.0 — 2026-10-01 - 0.14.0 — 2026-09-30 - 0.13.0 — 2026-09-29 - 0.12.0 — 2026-09-27 - 0.11.0 — 2026-09-24 - 0.10.2 — 2026-09-16 - 0.10.1 — 2026-09-11 - 0.10.0 — 2026-09-10 - 0.9.5 — 2026-09-08 - 0.9.4 — 2026-09-05 - 0.9.3 — 2026-08-27 - 0.9.1 — 2026-08-23 - … 78 more at https://npm.io/package/yuku-parser/versions ## README # yuku-parser A fast, spec-compliant JavaScript and TypeScript parser, part of [Yuku](https://yuku.fyi). - [Install](#install) - [Usage](#usage) - [The AST](#the-ast) - [Options](#options) - [Result](#result) - [Diagnostics](#diagnostics) - [Comments](#comments) - [Tokens](#tokens) ## Install ```bash npm install yuku-parser ``` It runs on Yuku's native core, installed for your platform. In browsers and edge runtimes, load the WebAssembly core from [`@yuku-core/wasm`](https://www.npmjs.com/package/@yuku-core/wasm) and pass it in as `core`. ## Usage ```js import { parse } from "yuku-parser"; const { program, comments, diagnostics } = parse("const x = 1 + 2;"); ``` ## The AST [ESTree](https://github.com/estree/estree) for JavaScript and JSX, identical to [Acorn](https://www.npmjs.com/package/acorn), and [TypeScript-ESTree](https://www.npmjs.com/package/@typescript-eslint/typescript-estree) for TypeScript, matching [Oxc](https://oxc.rs) for both. On top of the specs, it carries stage 3 [decorators](https://github.com/tc39/proposal-decorators), [import defer](https://github.com/tc39/proposal-defer-import-eval) and [import source](https://github.com/tc39/proposal-source-phase-imports) as `phase` on imports and `ImportExpression`, and the `hashbang` of `Program`. Every node type is exported, listed in the [type definitions](https://github.com/yuku-toolchain/yuku/blob/main/npm/yuku-types/index.d.ts). ```ts import type { Expression, Identifier, Node, Statement } from "yuku-parser"; ``` To walk, build, and check nodes, use [`yuku-ast`](https://www.npmjs.com/package/yuku-ast). For scopes and bindings, use [`yuku-analyzer`](https://www.npmjs.com/package/yuku-analyzer). ## Options ```js parse(source, { path: "src/app.tsx" }); ``` | Option | Values | Default | Description | | ---------------- | ----------------------------------------- | ---------- | -------------------------------------------------------------------------------------------------- | | `path` | a file path | none | Names the file in diagnostics. `lang` and `sourceType` default from its extension. | | `lang` | `"js"`, `"jsx"`, `"ts"`, `"tsx"`, `"dts"` | `"js"` | The syntax to parse. `.d.ts`, `.tsx`, `.ts`, and `.jsx` paths select their own. | | `sourceType` | `"module"`, `"script"`, `"commonjs"` | `"module"` | `"commonjs"` allows top-level `return`, and `.cjs` and `.cts` paths select it. | | `preserveParens` | `true`, `false` | `true` | Keep `ParenthesizedExpression` nodes. | | `semanticErrors` | `true`, `false` | `false` | Also report the early errors that need scopes, such as redeclarations and `break` outside a loop. | | `attachComments` | `true`, `false` | `false` | Also attach each comment to its node. See [Comments](#comments). | | `tokens` | `true`, `false` | `false` | Keep every token. See [Tokens](#tokens). | | `core` | a loaded core | native | The core that parses, see [`@yuku-core/wasm`](https://www.npmjs.com/package/@yuku-core/wasm). | An unknown `lang` or `sourceType` throws a `TypeError`. `langFromPath(path)` and `sourceTypeFromPath(path)` return the values a path implies. ## Result ```ts interface ParseResult { program: Program; comments: Comment[]; tokens?: TokenList; // with tokens: true diagnostics: Diagnostic[]; } ``` The parser recovers from errors, so a result with diagnostics still holds a tree of everything it could read. ## Diagnostics Every Yuku package reports diagnostics in one shape. ```ts interface Diagnostic { severity: "error" | "warning" | "hint" | "info"; message: string; path: string | null; // the path option start: number; // UTF-16 offsets, like nodes end: number; labels: { start: number; end: number; message: string }[]; help: string | null; } ``` ## Comments ```js const { comments } = parse(`// a line comment\nconst x = 1; /* a block comment */`); // [ // { type: "Line", value: " a line comment", start: 0, end: 17 }, // { type: "Block", value: " a block comment ", start: 31, end: 52 }, // ] ``` `attachComments: true` also hangs each comment on the node it sits next to, which [`yuku-codegen`](https://www.npmjs.com/package/yuku-codegen#comments) prints from, so comments move with their nodes. ```js const { program } = parse(`// header\nfunction foo() {} // trailing`, { attachComments: true }); program.body[0].comments; // [ // { type: "Line", position: "before", sameLine: false, value: " header" }, // { type: "Line", position: "after", sameLine: true, value: " trailing" }, // ] ``` `position` is `"before"`, `"after"`, or `"inside"` an otherwise empty node, such as `function f() { /* hi */ }`. ## Tokens `tokens: true` keeps every token in a `TokenList`, a view over the parser's token table where a token is an index. ```js import { parse, TokenKind } from "yuku-parser"; const { tokens } = parse(source, { tokens: true }); for (let i = 0; i < tokens.length; i++) { if (tokens.kind(i) === TokenKind.Arrow) console.log(tokens.start(i), tokens.text(i)); } ``` ```js tokens.kind(i) // one of TokenKind tokens.text(i) // its source text tokens.start(i) // UTF-16 offsets tokens.end(i) tokens.isKeyword(i) tokens.isReserved(i) // reserved unconditionally or in strict mode tokens.isUnconditionallyReserved(i) tokens.isStrictModeReserved(i) tokens.isIdentifierLike(i) // an identifier or any keyword tokens.isNumericLiteral(i) tokens.isBinaryOperator(i) tokens.isLogicalOperator(i) tokens.isUnaryOperator(i) tokens.isAssignmentOperator(i) tokens.precedence(i) // binary precedence, 0 when none tokens.newlineBefore(i) // what ASI reads tokens.escaped(i) tokens.invalidEscape(i) // a template chunk whose cooked value is undefined tokens.loneSurrogate(i) tokens.range(node) // [from, to) of the tokens inside a node tokens.first(node) tokens.last(node) tokens.before(nodeOrOffset) // the last token ending at or before it tokens.after(nodeOrOffset) // the first token starting at or after it tokens.at(offset) // the token containing an offset ``` The queries answer with an index, or `-1` when there is none. Tokens are as the parser resolved them, so a regex is one `RegexLiteral`, and comments are not tokens. The kinds are listed in [tokens.d.ts](https://github.com/yuku-toolchain/yuku/blob/main/npm/yuku-types/tokens.d.ts). ## License MIT --- _Source: https://npm.io/package/yuku-parser · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._