npm / es-module-lexer

es-module-lexer

What changed in es-module-lexer 2 to 3, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-20.

11 breaking2 security8 new APIs and options6 performance3 behavior and defaults1 tooling20 fixes and other

See which of these apply to your code, ranked, in your agent:

npx @unstale/cli init

es-module-lexer 334 changes

init is now a function, changing how developers use the API.
3.0.2release notes
This entry point is the asm.js build; the unmaintained pure-JS port is removed.
3.0.0release notes
New entry point with the v2-shaped API: parse returns only imports and exports, at is dropped, and re-exported imported names are reported in ln/ls/le.
3.0.0release notes
export default interface Foo now reports Foo as its local name.
3.0.0release notes
Reexports resolve to their originating import regardless of statement order; export * is represented as reexport-all and its import as reexport-star.
3.0.0release notes
Full-build records now use tagged unions discriminated by type, with descriptive fields replacing the terse v2 names and numeric type tags.
3.0.0release notes
ImportType is now a type-only union of named numeric literal aliases; no runtime enum is exported.
3.0.0release notes
initSync is no longer exported; parse initializes on first use.
3.0.0release notes
Node.js 18 or later is required.
3.0.0release notes
Invalid escape sequences now throw a parse error instead of yielding undefined.
3.0.0release notes

Module strings decode without eval, improving one-import parse speed and allowing Wasm builds under --disallow-code-generation-from-strings.
3.0.0release notes
Nesting past 1024 brackets or 512 dynamic imports now produces a parse error instead of memory corruption.
3.0.0release notes

A glob flag is added on dynamic imports.
3.0.1release notes
A specifier is added on import.meta.
3.0.1release notes
typeOnly is added on import.meta.
3.0.1release notes
Dynamic import attributes are typed null; attributesStart locates the options argument.
3.0.0release notes
Dynamic imports carry a best-effort probablyTypeOnly field in full builds.
3.0.0release notes
Full builds lex TypeScript type-only imports, exports, aliases, interfaces, and ambient declarations; type-only edges carry typeOnly.
3.0.0release notes

Reduces TypeScript lookahead work, improving lexer performance.
3.0.4release notes
Parser wrapper overhead was reduced.
3.0.2release notes
The full Wasm build uses SIMD scanning for long line comments and templates; the minimal build stays Wasm MVP.
3.0.0release notes

The minimal build enforces Wasm MVP and uses no post-MVP features.
3.0.0release notes
parse initializes Wasm synchronously on first call; await init is only required on browser main threads, and all four entry points share the parse/init API.
3.0.0release notes

Preserves complete import attribute metadata in parser results.
3.0.4release notes
Lexes / after a postfix non-null assertion as division.
3.0.4release notes
Fixes handling of ASI and repeated non-null assertions in TypeScript export bindings.
3.0.3release notes
Handles TypeScript generic commas in exported bindings.
3.0.3release notes
Minimal build reexports report no local name.
3.0.1release notes
Unannotated declare let/var no longer erases the following statement.
3.0.0release notes
Shorthand declare module no longer erases the following statement.
3.0.0release notes
A dynamic import with a single template-literal argument reports a glob specifier with each interpolation collapsed to *.
3.0.0release notes
Typed export binding lists now collect every declarator.
3.0.0release notes
export { type as } and type as as now follow TypeScript's specifier table.
3.0.0release notes
U+00A0 is treated as whitespace around import/export names.
3.0.0release notes

The lexer skips identifier and number runs, improving lexer performance.
2.3.2release notes
The lexer gates keywordStart on the next byte for i/c tokens.
2.3.1release notes
Node uses a fast native UTF-16 source copy into Wasm memory.
2.3.1release notes

Adds side-effects metadata to package.json, which can inform bundler behavior.
2.3.2release notes

The asm.js integer return type annotation is fixed.
2.3.2release notes
The sourcename is now forwarded through the pre-init parse path.
2.3.2release notes
WebAssembly memory can grow for sources over ~4MB, including in the minimal build.
2.3.0release notes
A method named import with two or more arguments is no longer treated as a dynamic import.
2.2.0release notes
Export var, let, and const declarations now detect every binding.
2.2.0release notes
The n field is now reported for dynamic imports using no-substitution template literals.
2.2.0release notes
Dynamic import attributes are always excluded from the specifier range.
2.1.0release notes
Handles new of conflict cases.
2.1.0release notes
A global reference issue has been fixed.
2.0.0release notes